#include <bits/stdc++.h>
using namespace std;

#define rep(i, l, r) for (int i = (int)(l); i<(int)(r); i++)
#define ll long long

int main() {
    int N; ll X; cin >> N >> X;
    vector<int> A(N+N+1);
    rep(i, 0, N) cin >> A[i];
    if (X <= N) {
        cout << A[X-1] << endl;
        return 0;
    }

    map<int, int> mp;
    rep(i, 0, N) mp[A[i]]++;

    set<int> st;
    for (int i = 0; i <= N; i++) st.insert(i);
    for (auto[key, val] : mp) st.erase(key);
    
    for (int i = N; i < 2*N+1; i++) {
        A[i] = *st.begin();
        if (++mp[A[i]] == 1) {
            st.erase(A[i]);
        }
        if (--mp[A[i-N]] == 0) {
            st.insert(A[i-N]);
        }
    }

    ll rest = X - N;
    if (rest%(N+1) == 0) {
        cout << A[2*N] << endl;
    }
    else {
        cout << A[N+rest%(N+1)-1] << endl;
    }
}