#include <bits/stdc++.h>
using namespace std;
int main() {
  long long niz[1000100], n, k;
  cin >> n >> k;
  for (int i = 0; i < n; i++) cin >> niz[i];
  long long l = 1, r = n;
  while (l < r) {
    long long s = (l + r + 1) / 2;
    if (s * (s + 1) / 2 >= k)
      r = s - 1;
    else
      l = s;
  }
  if (k == 1)
    cout << niz[0] << endl;
  else
    cout << niz[k - l * (l + 1) / 2 - 1] << endl;
  return 0;
}
