#include<iostream>
#include<vector>
#include<map>
#include<set>
using namespace std;

int main()
{
	int N;long long X;
	cin>>N>>X;
	vector<int>A(N);
	set<int> mex;
	map<int,int> count;
	for(int i=0;i<2e5+1000;++i)mex.emplace(i);
	for(int i=0;i<N;++i){
		cin>>A[i];
		mex.erase(A[i]);
		count[A[i]]++;
	}
	
	int loopEndIdx=0;
	int first = -1;
	for(int i=N;i<N*20;++i)
	{
		A.emplace_back(*mex.begin());
		count[*mex.begin()]++;
		if(*mex.begin()==first)
		{
			loopEndIdx = i;
			break;
		}
		if(i==N)first=*mex.begin();
		mex.erase(mex.begin());
		count[A[i-N]]--;
		if(count[A[i-N]]==0)
		{
			mex.emplace(A[i-N]);
		}
	}
	int loopLen = loopEndIdx - N;
	/*
	for(int i:A)cout << i << ' ';
	cout << endl;
	cout << "loopLen " << loopLen << endl;
	*/
	if(--X < N)
	{
		cout << A[X] << endl;
		return 0;
	}
	X -= N;
	cout << A[X%loopLen + N] << endl;
	

	/*
	for(int i=N;i<=N*20;++i)
	{
		int res = 0;
		for(int j=0;j<200;++j)
		{
			if(count[j]==0)
			{
				res = j;
				break;
			}
		}
		count[res]++;
		A.emplace_back(res);
		count[A[i-N]]--;
	}

	for(int i=0;i<100;++i) cout<<A[i] << ' ';
	*/

	
}