#include <bits/stdc++.h>
using namespace std;
int n;
long long res, k;
long long ar[100005];
int main() {
  int i, j, t, tc = 1, a, b;
  cin >> n >> k;
  long long res;
  for (i = 0; i < n; i++) cin >> ar[i];
  res = 0;
  for (i = 1; i <= n; i++) {
    res += i;
    if (res >= k) break;
  }
  res = (i * (i - 1) / 2) + 1;
  if (res == k) {
    cout << ar[0] << endl;
    return 0;
  }
  cout << ar[k - res] << endl;
  return 0;
}
