#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
const int N = 5e4 + 10;
const int M = 1e6 + 10;
int n, k, pre[M];
int id = -1;
int main()
{
scanf("%d%d", &n, &k);
for (int i = 1; i <= n; i ++)
{
int x;
scanf("%d", &x);
if (pre[x] && pre[x] + k >= i)
id = max(id, x);
pre[x] = i;
}
printf("%d", id);
return 0;
}