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