namespace test
{
    internal class Program
    {
        static void Main(string[] args)
        {
            cin = new input();
            mod = new mod(998244353);
            toolbox = new toolbox();
            Priority_Queue = new Priority_Queue(true);
            var sw = new System.IO.StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
            Console.SetOut(sw);
            toolbox.StartTimer();

            int q=cin.intreed();
            int k=cin.intreed();
            var tree=new BinaryTrie64();
            while(q-->0)
            {
                if(cin.intreed()==1)
                    tree.Insert(cin.longreed());
                else
                    if(tree.Size>=k)
                {
                    var val=tree[k];
                    System.Console.WriteLine(val);
                    tree.Erase(val);
                }
                else
                    System.Console.WriteLine(-1);
            }

            toolbox.PrintElapsedTime();
            Console.Out.Flush();
        }
        static input cin;
        static mod mod;
        static toolbox toolbox;
        static Priority_Queue Priority_Queue;
    }
    public class BinaryTrie64
    {
        private const int B = 64; // long は64ビット

        private class Node
        {
            public int Count;        // 部分木に含まれる要素数
            public Node Left;        // ビット0枝
            public Node Right;       // ビット1枝
            public Node()
            {
                Count = 0;
                Left = null;
                Right = null;
            }
        }

        private Node root = null;

        // ————————————————
        // 挿入／削除（点更新）
        // ————————————————
        private Node Add(Node t, long val, int b)
        {
            if (t == null) t = new Node();
            t.Count++;
            if (b < 0) return t;
            int bit = (int)((val >> b) & 1L);
            if (bit == 0)
                t.Left = Add(t.Left, val, b - 1);
            else
                t.Right = Add(t.Right, val, b - 1);
            return t;
        }

        private Node Sub(Node t, long val, int b)
        {
            if (t == null) return null;
            t.Count--;
            if (t.Count == 0) return null;
            if (b < 0) return t;
            int bit = (int)((val >> b) & 1L);
            if (bit == 0)
                t.Left = Sub(t.Left, val, b - 1);
            else
                t.Right = Sub(t.Right, val, b - 1);
            return t;
        }

        // ————————————————
        // XOR最小値／最大値取得
        // ————————————————
        private long GetMin(Node t, long val, int b)
        {
            if (t == null) throw new InvalidOperationException("Trie is empty");
            if (b < 0) return 0;
            int f = (int)((val >> b) & 1L);
            Node targetChild = (f == 0) ? t.Left : t.Right;
            if (targetChild == null)
            {
                f = 1 - f;
                targetChild = (f == 0) ? t.Left : t.Right;
            }
            long res = GetMin(targetChild, val, b - 1);
            return res | ((long)f << b);
        }

        // ————————————————
        // k番目小さい要素取得
        // ————————————————
        private long Get(Node t, int k, int b)
        {
            if (t == null || k < 1 || k > t.Count)
                throw new ArgumentOutOfRangeException(nameof(k));
            
            long result = 0;
            while (b >= 0 && t != null)
            {
                int leftCount = t.Left != null ? t.Left.Count : 0;
                if (k <= leftCount)
                {
                    t = t.Left;
                }
                else
                {
                    result |= (1L << b);
                    t = t.Right;
                    k -= leftCount;
                }
                b--;
            }
            return result;
        }

        // ————————————————
        // lower_bound／upper_bound の内部：要素 < val の個数を数える　
        // ————————————————
        private int CountLower(Node t, long val, int b)
        {
            if (t == null || b < 0) return 0;
            int bit = (int)((val >> b) & 1L);
            int cnt = (bit == 1 && t.Left != null) ? t.Left.Count : 0;
            Node targetChild = (bit == 0) ? t.Left : t.Right;
            return cnt + CountLower(targetChild, val, b - 1);
        }

        // ————————————————
        // public API
        // ————————————————

        /// <summary>集合の要素数を返す。</summary>
        public int Size => root != null ? root.Count : 0;

        /// <summary>空かどうかを返す。</summary>
        public bool IsEmpty => root == null;

        /// <summary>x を集合に追加する。</summary>
        public void Insert(long x) => root = Add(root, x, B - 1);

        /// <summary>x を集合から削除する（存在しない場合は何もしない）。</summary>
        public void Erase(long x) => root = Sub(root, x, B - 1);

        /// <summary>x XOR v が最小となる v を返す。</summary>
        public long MinXor(long x) => GetMin(root, x, B - 1);

        /// <summary>x XOR v が最大となる v を返す。</summary>
        public long MaxXor(long x) => GetMin(root, ~x, B - 1);

        /// <summary>集合内の最小要素を返す。</summary>
        public long MinElement() => MinXor(0);

        /// <summary>集合内の最大要素を返す。</summary>
        public long MaxElement() => MaxXor(0);

        /// <summary>
        /// lower_bound(x)：
        /// 集合内で値 x 以上の最小の要素の「番号」を取得します。
        /// ここで「番号」とは小さい方から何番目か（1-indexed）を指します。  
        /// ⇒ 内部的には要素 ＜ x の個数 + 1を返します。
        /// つまり、集合の最大値より大きいvalを投げると、集合の要素数 + 1が返ってくる
        /// </summary>
        public int LowerBound(long val) => CountLower(root, val, B - 1) + 1;

        /// <summary>
        /// upper_bound(x)：
        /// 集合内で値 x より大きい最小の要素の「番号」を取得します。
        /// ここで「番号」とは小さい方から何番目か（1-indexed）を指します。  
        /// ⇒ 内部的には要素 ≤ x の個数 + 1を返します（val+1 を lower_bound しているため）。
        /// つまり、集合の最大値以上のvalを投げると、集合の要素数 + 1が返ってくる
        /// </summary>
        public int UpperBound(long val) => CountLower(root, val + 1, B - 1) + 1;

        /// <summary>k 番目（1-indexed）に小さい要素を返す。</summary>
        public long this[int k] => Get(root, k, B - 1);

        /// <summary>要素 val の集合内での個数を返す。</summary>
        public int Count(long val)
        {
            Node t = root;
            for (int i = B - 1; i >= 0 && t != null; i--)
            {
                int bit = (int)((val >> i) & 1L);
                t = (bit == 0) ? t.Left : t.Right;
            }
            return t != null ? t.Count : 0;
        }
    }


    public static class Extensions
    {
        public static Dictionary<T, int> safe_addtion_for_dictionary_int<T>(this Dictionary<T, int> dic, T key)
        {
            if (dic.ContainsKey(key))
                dic[key]++;
            else
                dic.Add(key, 1);
            return dic;
        }

        public static Dictionary<T, long> safe_addtion_for_dictionary_long<T>(this Dictionary<T, long> dic, T key)
        {
            if (dic.ContainsKey(key))
                dic[key]++;
            else
                dic.Add(key, 1);
            return dic;
        }

        public static Dictionary<T, List<T2>> safe_addtion_for_list_in_dictionary<T, T2>(this Dictionary<T, List<T2>> dic, T key, T2 value)
        {
            if (dic.ContainsKey(key))
                dic[key].Add(value);
            else
                dic.Add(key, new List<T2>() { value });
            return dic;
        }

        public static T list_pop_back<T>(this List<T> a)
        {
            var k = a[a.Count - 1];
            a.RemoveAt(a.Count - 1);
            return k;
        }

        public static T chmin<T>(ref this T a, T b)
            where T : struct, IComparable
        {
            if (a.CompareTo(b) > 0)
                return a = b;
            else
                return a;
        }
        public static T chmax<T>(ref this T a, T b)
            where T : struct, IComparable
        {
            if (a.CompareTo(b) < 0)
                return a = b;
            else
                return a;
        }

    }

    internal class input
    {
        string[] soloinput;
        int t;
        public input()
        {
            soloinput = new string[0];
            t = 0;
        }
        public string soloreed()
        {
            if (t < soloinput.Length)
            {
                return soloinput[t++];
            }
            string input = Console.ReadLine();
            while (input == "")
            {
                input = Console.ReadLine();
            }
            soloinput = input.Split(" ");
            t = 0;
            return soloinput[t++];
        }
        public int intreed()
        {
            return int.Parse(soloreed());
        }
        public int[] arrayint(int N)
        {
            int[] A = new int[N];
            for (int i = 0; i < N; i++)
            {
                A[i] = intreed();
            }
            return A;
        }
        public long longreed()
        {
            return long.Parse(soloreed());
        }
        public long[] arraylong(long N)
        {
            long[] A = new long[N];
            for (long i = 0; i < N; i++)
            {
                A[i] = longreed();
            }
            return A;
        }
        public decimal decimalreed()
        {
            return decimal.Parse(soloreed());
        }
        public decimal[] arraydecimal(long N)
        {
            decimal[] A = new decimal[N];
            for (decimal i = 0; i < N; i++)
            {
                A[(long)i] = decimalreed();
            }
            return A;
        }


    }

    internal class mod
    {
        public long T { get; set; }
        public mod(long mod = 1000000007)
        {
            T = mod;
        }
        public long addition(long A, long B)
        {
            long C = A + B;
            return (long)C % T;
        }
        public long subtraction(long A, long B)
        {
            return ( (A % T) - (B % T) + T ) % T;
        }
        public long multiplication(long A, long B)
        {
            return ((A % T) * (B % T)) % T;
        }

    }

    internal class toolbox
    {

        string Y = "Yes";
        string N = "No";
        static input cin;
        private DateTime? startTime;
        public toolbox()
        {
            cin = new input();
        }

        public long[] CumulativeSum(long[] A, bool mode = true)
        {
            if (mode == false) Array.Reverse(A);
            long[] back = new long[A.Length + 1];
            back[0] = 0;
            for (int i = 1; i <= A.Length; i++)
            {
                back[i] = back[i - 1] + A[i - 1];
            }
            if (mode == false) Array.Reverse(A);
            return back;
        }

        public long[] Eratosthenes(long A)
        {
            A++;
            var back = new List<long>();
            bool[] ch = new bool[A];
            for (int i = 2; i < A; i++) ch[i] = true;
            for (long i = 2; i < Math.Sqrt(A); i++)
            {
                if (ch[i] == true)
                {
                    back.Add(i);
                    for (long t = 1; i * t < A; t++)
                    {
                        ch[i * t] = false;
                    }
                }
            }
            for (long i = 0; i < A; i++)
            {
                if (ch[i] == true) back.Add(i);
            }
            return back.Distinct().ToArray();
        }
        public void Swap<T>(ref T a, ref T b)
        {
            var i = a;
            a = b;
            b = i;
        }

        public void LSwap<T>(ref List<T> A, int a, int b)
        {
            var i = A[a];
            A[a] = A[b];
            A[b] = i;
        }

        public long Gcd(long A, long B)
        {
            while (A != 0)
            {
                B %= A;
                Swap(ref A, ref B);
            }
            return B;
        }

        public long[] AllDivisors(long N)
        {
            var back = new List<long>();
            for (int i = 1; Math.Pow(i, 2) <= N; i++)
            {
                if (N % i == 0)
                {
                    back.Add(i);
                    back.Add(N / i);
                }
            }
            return back.Distinct().ToArray();
        }

        public static IEnumerable<T[]> ExhaustiveEnumeration<T>(IEnumerable<T> indata)
        {
            if (indata.Count() == 1) yield return new T[] { indata.First() };
            foreach (var i in indata)
            {
                var used = new T[] { i };
                var unused = indata.Except(used);
                foreach (var t in ExhaustiveEnumeration(unused))
                    yield return used.Concat(t).ToArray();
            }
            //How to use
            //var allpattern = toolbox.ExhaustiveEnumeration(Enumerable.Range(1, N));
        }

        public bool[,] bitallsearch(int N)
        {
            bool[,] back = new bool[(int)Math.Pow(2, N), N];
            for (int i = 0; i < Math.Pow(2, N); i++)
            {
                for (int t = 0; t < N; t++)
                {
                    var k = (i >> t) & 1;
                    if (k == 1)
                    {
                        back[i, t] = true;
                    }
                }
            }
            return back;
        }

        public static int BS<T>(T[] A, T key)
            where T : IComparable
        {
            //このコード、定数倍が大変な事になってるので標準ライブラリを使いましょう(BinarySearch)
            int left = 0;
            int right = A.Length;
            int mid = 0;
            while (left < right)
            {
                mid = (left + right) / 2;
                if (A[mid].CompareTo(key) == 0)
                    return mid;
                else if (A[mid].CompareTo(key) > 0)
                    right = mid;
                else if (A[mid].CompareTo(key) < 0)
                    left = mid + 1;
            }
            return -1;
        }

        public static int lower_bound<T>(T[] a, T v)
        {
            return lower_bound(a, v, Comparer<T>.Default);
        }

        public static int lower_bound<T>(T[] A, T key, Comparer<T> v)
        {
            int left = 0;
            int right = A.Length - 1;
            int mid = 0;
            var W = 0;
            while (left <= right)
            {
                mid = (left + right) / 2;
                W = v.Compare(A[mid], key);
                if (W == -1)
                    left = mid + 1;
                else
                    right = mid - 1;
            }
            return left;
        }

        public long[] prime_factorize(long N)
        {
            long T = N;
            var back = new List<long>();
            for (long i = 2; i * i <= T; i++)
            {
                if (T % i != 0) continue;
                while (T % i == 0)
                {
                    back.Add(i);
                    T /= i;
                }
            }
            if (T != 1) back.Add(T);
            return back.ToArray();
        }

        public long[] One_dimensional_Coordinate_Compression(long[] A)
        {
            long[] back = new long[A.Length];
            var T = A.Distinct().ToList();
            T.Sort();
            for (int i = 0; i < A.Length; i++)
                back[i] = T.BinarySearch(A[i]);
            return back;
        }

        public void setYN(string A = "Yes", string B = "No")
        {
            Y = A;
            N = B;
        }

        public void YN(bool ans)
        {
            if (ans)
                Console.WriteLine(Y);
            else
                Console.WriteLine(N);
        }

        public string[] x_dekakou(int H, int W)
        {
            var s = new string[H + 2];
            for (int i = 0; i < W + 2; i++)
            {
                s[0] += "x";
                s[H + 1] += "x";
            }
            for (int i = 1; i < H + 1; i++)
            {
                //x場外　.白　#黒
                s[i] = "x" + Console.ReadLine().Replace(" ", "") + "x";
            }
            return s;
        }

        public List<List<char>> x_dekakou_char(int H, int W)
        {
            var grid = new List<List<char>>(H + 2);

            var border = new List<char>(W + 2);
            for (int i = 0; i < W + 2; i++)
                border.Add('x');
            grid.Add(new List<char>(border));

            for (int i = 0; i < H; i++)
            {
                var line = Console.ReadLine()?.Replace(" ", "") ?? string.Empty;
                var row = new List<char>(W + 2);
                row.Add('x');
                foreach (var c in line)
                    row.Add(c);
                row.Add('x');
                grid.Add(row);
            }

            grid.Add(new List<char>(border));
            return grid;
        }

        public List<List<int>> x_dekakou_string(int H, int W)
        {
            var back = new List<List<int>>();
            for (int i = 0; i < H + 2; i++)
                back.Add(Enumerable.Repeat<int>(-1, W + 2).ToList());
            for (int i = 0; i < W + 2; i++)
            {
                back[0][i] = -1;
                back[H + 1][i] = -1;
            }
            for (int i = 1; i <= H; i++)
            {
                back[i][0] = -1;
                back[i][W + 1] = -1;
                for (int t = 1; t <= W; t++)
                    back[i][t] = cin.intreed();
            }
            return back;
        }
        /// <summary>
        /// 配列の指定位置以降を反転する
        /// </summary>
        /// <param name="array">反転対象の配列</param>
        /// <param name="begin">反転開始位置（この位置以降が反転される）</param>
        private void Reverse<T>(T[] array, int begin) where T : IComparable<T>
        {
            // 反転する要素が2個未満の場合は何もしない
            if (array.Length - begin < 2) return;

            // 両端から中央に向かって要素を交換
            int left = begin;
            int right = array.Length - 1;
            while (left < right)
            {
                Swap(ref array[left], ref array[right]);
                left++;
                right--;
            }
        }

        /// <summary>
        /// 配列を辞書順で次の順列に変更する
        /// 全ての順列を列挙するには、事前に Array.Sort() でソートした配列を渡すこと
        /// </summary>
        /// <param name="array">順列を生成する配列（事前ソート必須）</param>
        /// <returns>次の順列が存在する場合true、最大順列の場合false</returns>
        public bool NextPermutation<T>(T[] array) where T : IComparable<T>
        {
            // 辞書順で次に大きい順列を生成

            // 1. 右端から降順でない位置を探す
            int pivotIndex = -1;
            for (int i = array.Length - 2; i >= 0; i--)
            {
                if (array[i].CompareTo(array[i + 1]) < 0) // 昇順ペア発見
                {
                    pivotIndex = i;
                    break;
                }
            }

            // 最大順列に到達している場合
            if (pivotIndex == -1) return false;

            // 2. pivotより大きい最右の要素と交換
            for (int j = array.Length - 1; j > pivotIndex; j--)
            {
                if (array[pivotIndex].CompareTo(array[j]) < 0)
                {
                    Swap(ref array[pivotIndex], ref array[j]);
                    break;
                }
            }

            // 3. pivot以降を昇順に並べ直し
            Reverse(array, pivotIndex + 1);
            return true;

            // how to use
            // do{}while(NextPermutation)
        }

        /// <summary>
        /// 回文判定のコア処理（配列版）
        /// </summary>
        private bool IsPalindromeCore<T>(T[] array, int left, int right) where T : IComparable<T>
        {
            while (left < right)
            {
                if (array[left].CompareTo(array[right]) != 0)
                    return false;
                left++;
                right--;
            }
            return true;
        }

        /// <summary>
        /// 回文判定のコア処理（文字列版）
        /// </summary>
        private bool IsPalindromeCore(string str, int left, int right)
        {
            while (left < right)
            {
                if (str[left] != str[right])
                    return false;
                left++;
                right--;
            }
            return true;
        }

        /// <summary>
        /// 配列全体が回文かどうかを判定
        /// </summary>
        public bool IsPalindrome<T>(T[] array) where T : IComparable<T>
        {
            return IsPalindromeCore(array, 0, array.Length - 1);
        }

        /// <summary>
        /// 文字列全体が回文かどうかを判定
        /// </summary>
        public bool IsPalindrome(string str)
        {
            return IsPalindromeCore(str, 0, str.Length - 1);
        }

        /// <summary>
        /// 指定範囲が回文かどうかを判定（配列版）
        /// </summary>
        public bool IsPalindrome<T>(T[] array, int start, int end) where T : IComparable<T>
        {
            return IsPalindromeCore(array, start, end);
        }

        /// <summary>
        /// 指定範囲が回文かどうかを判定（文字列版）
        /// </summary>
        public bool IsPalindrome(string str, int start, int end)
        {
            return IsPalindromeCore(str, start, end);
        }

        /// <summary>
        /// 指定長さの部分配列に回文が含まれるかを判定
        /// </summary>
        public bool HasPalindrome<T>(T[] array, int length) where T : IComparable<T>
        {
            for (int i = 0; i <= array.Length - length; i++)
            {
                if (IsPalindromeCore(array, i, i + length - 1))
                    return true;
            }
            return false;
        }

        /// <summary>
        /// 指定長さの部分文字列に回文が含まれるかを判定
        /// </summary>
        public bool HasPalindrome(string str, int length)
        {
            for (int i = 0; i <= str.Length - length; i++)
            {
                if (IsPalindromeCore(str, i, i + length - 1))
                    return true;
            }
            return false;
        }


        public long modpow(long x, long p, long mod = 1000000007)
        {
            long result = 1;
            x %= mod;
            while (p > 0)
            {
                if (p % 2 == 1)        // pが奇数の場合
                {
                    result = (result * x) % mod;
                }
                x = (x * x) % mod;      // xを二乗（これが繰り返し二乗）
                p /= 2;                 // pを半分にする
            }
            return result;
        }

        public void StartTimer()
        {
            startTime = DateTime.Now;
        }

        public void PrintElapsedTime(bool error_output = true)
        {
            //標準出力ではなくて標準エラー出力を使ってるのでatcoderのジャッジはこの出力を無視する　つまり消さなくてok　便利だね
            if (startTime.HasValue)
            {
                var elapsed = DateTime.Now - startTime.Value;
                if (error_output)
                    Console.Error.WriteLine($"Elapsed time: {elapsed.TotalMilliseconds} ms");
                else
                    Console.WriteLine($"Elapsed time: {elapsed.TotalMilliseconds} ms");


            }
            else
            {
                Console.Error.WriteLine("Timer was not started.");
            }
        }
    }

    internal class Priority_Queue
    {
        toolbox toolbox = new toolbox();
        public List<(long, long)> Queue { get; private set; }
        /// <summary>
        /// true==>大きいやつから出るよ　false==>小さいやつからでるよ
        /// </summary>
        public bool revase { get; set; }
        public Priority_Queue(bool cnt = true)
        {
            Queue = new List<(long, long)>();
            revase = cnt;
        }

        public void Enqueue(long a, long b)
        {
            if (revase == false)
                a *= -1;
            int i = Queue.Count, t;
            Queue.Add((a, b));
            while (i != 0)
            {
                t = (i - 1) / 2;
                if (Queue[i].Item1 > Queue[t].Item1)
                {
                    var k = Queue[i];
                    Queue[i] = Queue[t];
                    Queue[t] = k;
                    i = t;
                }
                else
                {
                    break;
                }
            }
        }

        public (long, long) Dequeue()
        {
            int a = Queue.Count - 1;
            var back = Queue[0];
            Queue[0] = Queue[a];
            Queue.RemoveAt(a);
            for (int i = 0, j; (j = 2 * i + 1) < a;)
            {
                if (j != a - 1 && Queue[j].Item1 < Queue[j + 1].Item1)
                    j++;
                if (Queue[i].Item1 < Queue[j].Item1)
                {
                    var k = Queue[i];
                    Queue[i] = Queue[j];
                    Queue[j] = k;
                    i = j;
                }
                else
                {
                    break;
                }
            }
            if (revase == false)
                back.Item1 *= -1;
            return back;

        }

        public (long, long) GetPeek() => (revase ? Queue[0].Item1 : Queue[0].Item1 * -1, Queue[0].Item2);
    }

    internal class Generic_Priority_Queue<T>
    {
        toolbox toolbox = new toolbox();
        public List<(long, T)> Queue { get; private set; }
        /// <summary>
        /// true==>大きいやつから出るよ　false==>小さいやつからでるよ
        /// </summary>
        public bool revase { get; set; }
        public Generic_Priority_Queue(bool cnt = true)
        {
            Queue = new List<(long, T)>();
            revase = cnt;
        }

        public void Enqueue(long a, T b)
        {
            if (revase == false)
                a *= -1;
            int i = Queue.Count, t;
            Queue.Add((a, b));
            while (i != 0)
            {
                t = (i - 1) / 2;
                if (Queue[i].Item1 > Queue[t].Item1)
                {
                    var k = Queue[i];
                    Queue[i] = Queue[t];
                    Queue[t] = k;
                    i = t;
                }
                else
                {
                    break;
                }
            }
        }

        public (long, T) Dequeue()
        {
            int a = Queue.Count - 1;
            var back = Queue[0];
            Queue[0] = Queue[a];
            Queue.RemoveAt(a);
            for (int i = 0, j; (j = 2 * i + 1) < a;)
            {
                if (j != a - 1 && Queue[j].Item1 < Queue[j + 1].Item1)
                    j++;
                if (Queue[i].Item1 < Queue[j].Item1)
                {
                    var k = Queue[i];
                    Queue[i] = Queue[j];
                    Queue[j] = k;
                    i = j;
                }
                else
                {
                    break;
                }
            }
            if (revase == false)
                back.Item1 *= -1;
            return back;

        }

        public (long, T) get_first()
        {
            if (Queue.Count == 0)
                return (default(long), default(T));
            else
                return Queue[0];
        }
    }

}