#include <bits/stdc++.h>
const int N = 1000000;
int id[N + 10];
int main() {
  int n = 0;
  long long k = 0;
  scanf("%d", &n);
  std::cin >> k;
  for (int i = 1; i <= n; i++) scanf("%d", id + i);
  for (int i = 1; i <= n; i++) {
    if (k <= 1LL * i) {
      printf("%d\n", id[k]);
      break;
    }
    k -= i;
  }
  return 0;
}
