#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define FORR2(x,y,arr) for(auto& [x,y]:arr)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
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(a>b){a=b;return 1;}return 0;}
//-------------------------------------------------------

int N;
ll A[404040];
ll X;
void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N>>X;
	set<int> V;
	FOR(i,N+2) V.insert(i);
	map<int,int> M;
	for(i=1;i<=N;i++) {
		cin>>A[i];
		M[A[i]]++;
		V.erase(A[i]);
	}
	for(i=N+1;i<=2*N+5;i++) {
		A[i]=*V.begin();
		if(--M[A[i-N]]==0) V.insert(A[i-N]);
		if(M[A[i]]++==0) V.erase(A[i]);
	}
	
	if(X<=2*N+5) {
		cout<<A[X]<<endl;
		return;
	}
	for(i=2*N+4;i>=0;i--) if(A[i]==A[2*N+5]) {
		ll lp=2*N+5-i;
		X=(X-i)%lp+i;
		cout<<A[X]<<endl;
		break;
	}
	

}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	cout.tie(0); solve(); return 0;
}