using System;
using System.Linq;
using System.Collections.Generic;
using Debug = System.Diagnostics.Debug;
using StringBuilder = System.Text.StringBuilder;
using Number = System.Int64;
namespace Program
{
    public class Solver
    {

        public void Solve()
        {
            var n = sc.Integer();
            var k = sc.Integer();
            var u = sc.Long();
            var a = sc.Long(n - 1);
            Array.Sort(a);
            var ok = false;
            var l = 0; var r = n - 1;
            for (int _ = 0; _ < 20; _++)
            {
                var m = (l + r) / 2;
                var v = u + a[m];
                var s = new Set<long>();
                for (int i = n - 2; i >= 0; i--)
                    if (i != m) s.Add(a[i]);
                var cnt = 0;
                while (s.Count >= 2)
                {
                    var min = s[0];
                    s.RemoveAt(0);
                    var lb = s.UpperBound(v - min);
                    if (lb < s.Count)
                    {
                        cnt++;
                        s.RemoveAt(lb);
                    }
                }
                if (cnt < k) { ok = true; r = m; }
                else l = m;
            }
            if (!ok) IO.Printer.Out.WriteLine(-1);
            else IO.Printer.Out.WriteLine(a[r]);


        }
        public IO.StreamScanner sc = new IO.StreamScanner(Console.OpenStandardInput());
        static T[] Enumerate<T>(int n, Func<int, T> f) { var a = new T[n]; for (int i = 0; i < n; ++i) a[i] = f(i); return a; }
        static public void Swap<T>(ref T a, ref T b) { var tmp = a; a = b; b = tmp; }
    }
}

#region main
static class Ex
{
    static public string AsString(this IEnumerable<char> ie) { return new string(System.Linq.Enumerable.ToArray(ie)); }
    static public string AsJoinedString<T>(this IEnumerable<T> ie, string st = " ") { return string.Join(st, ie); }
    static public void Main()
    {
        var solver = new Program.Solver();
        solver.Solve();
        Program.IO.Printer.Out.Flush();
    }
}
#endregion
#region Ex
namespace Program.IO
{
    using System.IO;
    using System.Text;
    using System.Globalization;
    public class Printer: StreamWriter
    {
        static Printer() { Out = new Printer(Console.OpenStandardOutput()) { AutoFlush = false }; }
        public static Printer Out { get; set; }
        public override IFormatProvider FormatProvider { get { return CultureInfo.InvariantCulture; } }
        public Printer(System.IO.Stream stream) : base(stream, new UTF8Encoding(false, true)) { }
        public Printer(System.IO.Stream stream, Encoding encoding) : base(stream, encoding) { }
        public void Write<T>(string format, T[] source) { base.Write(format, source.OfType<object>().ToArray()); }
        public void WriteLine<T>(string format, T[] source) { base.WriteLine(format, source.OfType<object>().ToArray()); }
    }
    public class StreamScanner
    {
        public StreamScanner(Stream stream) { str = stream; }
        public readonly Stream str;
        private readonly byte[] buf = new byte[1024];
        private int len, ptr;
        public bool isEof = false;
        public bool IsEndOfStream { get { return isEof; } }
        private byte read()
        {
            if (isEof) return 0;
            if (ptr >= len) { ptr = 0; if ((len = str.Read(buf, 0, 1024)) <= 0) { isEof = true; return 0; } }
            return buf[ptr++];
        }
        public char Char() { byte b = 0; do b = read(); while ((b < 33 || 126 < b) && !isEof); return (char)b; }

        public string Scan()
        {
            var sb = new StringBuilder();
            for (var b = Char(); b >= 33 && b <= 126; b = (char)read())
                sb.Append(b);
            return sb.ToString();
        }
        public string ScanLine()
        {
            var sb = new StringBuilder();
            for (var b = Char(); b != '\n'; b = (char)read())
                if (b == 0) break;
                else if (b != '\r') sb.Append(b);
            return sb.ToString();
        }
        public long Long()
        {
            if (isEof) return long.MinValue;
            long ret = 0; byte b = 0; var ng = false;
            do b = read();
            while (b != 0 && b != '-' && (b < '0' || '9' < b));
            if (b == 0) return long.MinValue;
            if (b == '-') { ng = true; b = read(); }
            for (; true; b = read())
            {
                if (b < '0' || '9' < b)
                    return ng ? -ret : ret;
                else ret = ret * 10 + b - '0';
            }
        }
        public int Integer() { return (isEof) ? int.MinValue : (int)Long(); }
        public double Double() { var s = Scan(); return s != "" ? double.Parse(s, CultureInfo.InvariantCulture) : double.NaN; }
        private T[] enumerate<T>(int n, Func<T> f)
        {
            var a = new T[n];
            for (int i = 0; i < n; ++i) a[i] = f();
            return a;
        }

        public char[] Char(int n) { return enumerate(n, Char); }
        public string[] Scan(int n) { return enumerate(n, Scan); }
        public double[] Double(int n) { return enumerate(n, Double); }
        public int[] Integer(int n) { return enumerate(n, Integer); }
        public long[] Long(int n) { return enumerate(n, Long); }
    }
}
#endregion
#region Set<T>
public class Set<T>
    where T : IComparable<T>
{

    Node root = Node.NIL;

    public int Count { get { return root.cnt; } }
    public void Add(T v) { Insert(v, LowerBound(v)); }
    public bool Remove(T v)
    {
        if (EqualRange(v) == 0) return false;
        RemoveAt(LowerBound(v));
        return true;
    }
    #region Impl
    public void Insert(T v, int k)
    {
        root = insert(root, v, k);
    }
    public void RemoveAt(int k)
    {
        root = removeat(root, k);
    }
    public int EqualRange(T v) { return UpperBound(v) - LowerBound(v); }
    public int LowerBound(T v) { return lowerBound(root, v); }
    public int UpperBound(T v) { return upperBound(root, v); }
    public T this[int k] { get { return find(root, k); } }
    Node insert(Node t, T v, int k)
    {
        Debug.Assert(t.cnt >= k);
        if (t == Node.NIL) return new Node(v);
        if (t.lst.cnt >= k)
            t.lst = insert(t.lst, v, k);
        else
            t.rst = insert(t.rst, v, k - t.lst.cnt - 1);
        t.Update();

        if (t.lst.h - t.rst.h == -2)
        {
            if (t.rst.lst.h - t.rst.rst.h > 0) t.rst = rotR(t.rst);
            t = rotL(t);
        }
        else if (t.lst.h - t.rst.h == 2)
        {
            if (t.lst.lst.h - t.lst.rst.h < 0) t.lst = rotL(t.lst);
            t = rotR(t);
        }
        t.Update();
        return t;
    }
    Node removeat(Node t, int k)
    {
        Debug.Assert(t.cnt > k);
        var cnt = t.lst.cnt;
        if (cnt < k) t.rst = removeat(t.rst, k - cnt - 1);
        else if (cnt > k) t.lst = removeat(t.lst, k);
        else
        {
            if (cnt == 0) return t.rst;
            if (t.rst.cnt == 0) return t.lst;

            t.val = find(t, k - 1);
            t.lst = removeat(t.lst, k - 1);
        }
        t.Update();
        if (t.lst.h - t.rst.h == -2)
        {
            if (t.rst.lst.h - t.rst.rst.h > 0) t.rst = rotR(t.rst);
            t = rotL(t);
        }
        else if (t.lst.h - t.rst.h == 2)
        {
            if (t.lst.lst.h - t.lst.rst.h < 0) t.lst = rotL(t.lst);
            t = rotR(t);
        }
        else t.Update();
        return t;
    }

    int lowerBound(Node t, T v)
    {
        if (t.cnt == 0) return 0;
        if (v.CompareTo(t.val) <= 0) return lowerBound(t.lst, v);
        else return t.lst.cnt + 1 + lowerBound(t.rst, v);
    }
    int upperBound(Node t, T v)
    {
        if (t.cnt == 0) return 0;
        if (t.val.CompareTo(v) <= 0) return t.lst.cnt + 1 + upperBound(t.rst, v);
        else return upperBound(t.lst, v);
    }
    T find(Node t, int k)
    {
        Debug.Assert(k < t.cnt);
        if (k == t.lst.cnt) return t.val;
        else if (k < t.lst.cnt) return find(t.lst, k);
        else return find(t.rst, k - (t.lst.cnt + 1));
    }
    Node rotR(Node t)
    {
        var l = t.lst;
        var lr = l.rst;
        l.rst = t;
        t.lst = lr;
        t.Update();
        l.Update();
        return l;
    }
    Node rotL(Node t)
    {
        var r = t.rst;
        var rl = r.lst;
        t.rst = rl;
        r.lst = t;
        t.Update();
        r.Update();
        return r;
    }
    #endregion
    class Node
    {
        static public readonly Node NIL = new Node();
        public int h;
        public int cnt;
        internal T val;
        internal Node lst, rst;
        private Node() { }
        internal Node(T v) { h = 1; cnt = 1; val = v; lst = NIL; rst = NIL; }
        public void Update()
        {
            if (cnt == 0) return;
            h = 1 + Math.Max(lst.h, rst.h);
            cnt = 1 + lst.cnt + rst.cnt;
        }
        public override string ToString()
        {
            return string.Format("count:{0}, value:{1}", cnt, val);
        }
        public T[] Items { get { return items(this); } }
        static public T[] items(Node t)
        {
            var ret = new T[t.cnt];
            var ptr = 0;
            dfs(t, ref ptr, ret);
            return ret;
        }
        static void dfs(Node t, ref int ptr, T[] ret)
        {
            if (t == Node.NIL) return;
            dfs(t.lst, ref ptr, ret);
            ret[ptr++] = t.val;
            dfs(t.rst, ref ptr, ret);
        }
    }
    public T[] Items { get { return root.Items; } }
    public override string ToString() { return string.Format("Count = {0}", Count); }

}
#endregion