#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, k, c = 1, a = 2;
  cin >> n >> k;
  long long arr[n];
  for (long long i = 0; i < n; i++) {
    cin >> arr[i];
  }
  while (c < k) {
    c += a;
    a++;
  }
  a--;
  c -= a;
  k -= c;
  cout << arr[k - 1] << endl;
}
