//#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using lint = long long;
constexpr lint mod = 998244353;
#define all(x) begin(x), end(x)
#define bitcount(n) __builtin_popcountll((lint)(n))
#define fcout cout << fixed << setprecision(15)
#define highest(x) (63 - __builtin_clzll(x))
#define rep(i, n) for(int i = 0; i < int(n); i++)
#define rep2(i, l, r) for(int i = int(l); i < int(r); i++)
#define repr(i, n) for(int i = int(n) - 1; i >= 0; i--)
#define repr2(i, l, r) for(int i = int(r) - 1; i >= int(l); i--)
constexpr int inf9 = 1e9; constexpr lint inf18 = 1e18;
inline void Yes(bool condition){ if(condition) cout << "Yes" << endl; else cout << "No" << endl; }
template<class itr> void array_output(itr start, itr goal){ for(auto i = start; i != goal; i++) cout << (i == start ? "" : " ") << (*i); cout << endl; }
template<class itr> void cins(itr first, itr last){ for(auto i = first; i != last; i++){ cin >> (*i); } }
template<class T> T gcd(T a, T b){ if(b) return gcd(b, a % b); else return a; }
template<class T> T lcm(T a, T b){ return a / gcd(a, b) * b; }
template<class T> bool chmax(T &a, const T &b){ if(a < b){ a = b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b){ if(b < a){ a = b; return 1; } return 0; }
inline int has(lint i, int j){ return (i >> j) & 1; }
int dy[4] = {1, 0, -1, 0}; int dx[4] = {0, 1, 0, -1};
bool is_inside(lint y, lint x, lint H, lint W){ return (0 <= y && y < H && 0 <= x && x < W); }

struct io_init {
    io_init() {
        cin.tie(nullptr); cout.tie(nullptr);
        std::ios::sync_with_stdio(false);
    }
} io_init;

template<class T, int BIT_COUNT = -1>
struct BinaryTrie{
    struct Node {
        Node *child[2];
        int under_cnt;
        
        Node() : child{nullptr, nullptr}, under_cnt(0) {}
    };
    
    int B;
    Node *root;
    
    BinaryTrie() : root(new Node()) {
        if(BIT_COUNT == -1){
            B = numeric_limits<T>::digits + int(numeric_limits<T>::is_signed);
        }else{
            B = BIT_COUNT;
        }
    }
    
    void insert(T x){
        Node *at = root;
        repr(i, B){
            (at -> under_cnt)++;
            
            bool d = ((x >> i) & 1);
            if(!(at -> child[d])) (at -> child[d]) = new Node();
            at = at -> child[d];
        }
        (at -> under_cnt)++;
    }
    
    int count(T x){
        Node *at = root;
        repr(i, B){
            bool d = ((x >> i) & 1);
            at = at -> child[d];
            if(!at) return 0;
        }
        return at -> under_cnt;
    }
    
    bool erase(T x){
        Node *at = root;
        repr(i, B){
            bool d = ((x >> i) & 1);
            at = at -> child[d];
            if(!at) return false;
        }
        
        at = root;
        repr(i, B){
            (at -> under_cnt)--;
            
            bool d = ((x >> i) & 1);
            at = at -> child[d];
        }
        (at -> under_cnt)--;
        return true;
    }
    
    int size(){
        return root -> under_cnt;
    }
    
    T kth_element(int k){
        assert(0 <= k && k < size());
        k++;
        
        Node *at = root;
        T ans = 0, one = 1;
        repr(i, B){
            int l_cnt = (at -> child[0] ? at -> child[0] -> under_cnt : 0);
            if(k <= l_cnt){
                at = at -> child[0];
            }else{
                at = at -> child[1];
                k -= l_cnt;
                ans += (one << i);
            }
        }
        return ans;
    }
};

int main(){
    int q, k;
    cin >> q >> k;
    k--;
    BinaryTrie<lint> tree;
    rep(_, q){
        int t;
        cin >> t;
        if(t == 1){
            lint x;
            cin >> x;
            tree.insert(x);
        }else{
            if(tree.size() < k + 1){
                cout << -1 << endl;
            }else{
                lint ans = tree.kth_element(k);
                cout << ans << endl;
                tree.erase(ans);
            }
        }
    }
}