#include <bits/stdc++.h>
using namespace std;
int main(){
	int N;
	long long X;
	cin >> N >> X;
	vector<int> A(N);
	for (int i = 0; i < N; i++){
		cin >> A[i];
	}
	set<int> st;
	for (int i = 0; i < 1000000; i++){
		st.insert(i);
	}
	map<int, int> mp;
	for (int i = 0; i < N; i++){
		mp[A[i]]++;
		if (st.count(A[i])){
			st.erase(A[i]);
		}
	}
	for (int i = 0; i < N * 2; i++){
		A.push_back(*st.begin());
		mp[A[i]]--;
		if (mp[A[i]] == 0){
			st.insert(A[i]);
		}
		
		mp[A.back()]++;
		if (mp[A.back()] == 1 and st.count(A.back())){
			st.erase(A.back());
		}
	}
	X--;
	if (X < (long long) A.size()){
		cout << A[X] << endl;
	} else {
		cout << A[A.size() - N - 1 + (X - A.size()) % (N + 1)] << endl;
	}
}