#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using mint = modint998244353;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using vmi = vector<mint>;
using vvmi = vector<vmi>;
using vvvmi = vector<vvmi>;
#define all(a) (a).begin(), (a).end()
#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
#define rep(i, n) rep2(i, 0, n)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define drep(i, n) drep2(i, n, 0)

int main(){
    ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    int n; ll x; cin >> n >> x;
    vi a(n), cnt(n+1, 0); rep(i, n){
        cin >> a[i];
        int m = (a[i] < n ? a[i] : n);
        cnt[m]++;
    }
    if(x <= n){
        cout << a[x-1] << endl;
        return 0;
    }
    set<int> st; rep(i, n+1){
        if(cnt[i] == 0)st.insert(i);
    }
    vi b(n+1);
    rep(i, n+1){
        b[i] = *st.begin();
        cnt[b[i]]++;
        st.erase(b[i]);
        if(i == n)break;
        cnt[a[i]]--;
        if(cnt[a[i]] == 0)st.insert(a[i]);
    }
    ll base = x - n;
    cout << b[(base - 1) % (n+1)] << endl;

    return 0;
}