#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n, a1[100000], a, k, x;
  cin >> n;
  cin >> k;
  a = 1;
  x = 1;
  for (int i = 0; i < n; i++) cin >> a1[i];
  while (a < k) {
    x++;
    a += x;
  }
  k = k - (a - x);
  cout << a1[k - 1];
  return 0;
}
