#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ;
  long long int n, k;
  cin >> n >> k;
  int a[n + 1];
  for (int i = (1); i <= (n); i++) cin >> a[i];
  long long int d = 1 + 8 * k;
  long long int x = (long long int)floor(((sqrt(d) - 1) / 2));
  if (n == 1)
    cout << a[1] << endl;
  else {
    if ((x * (x + 1)) / 2 == k)
      cout << a[x] << endl;
    else
      cout << a[k - (x * (x + 1)) / 2] << endl;
  }
  return 0;
}
