#include <bits/stdc++.h>
using namespace std;
int main() {
  int N, K, i, *mas;
  cin >> N >> K;
  mas = new int[N];
  for (i = 0; i < N; i++) cin >> mas[i];
  int otv = 0;
  i = 1;
  while (otv < K) {
    otv += i;
    i++;
  }
  i--;
  cout << mas[i - otv + K - 1];
  return 0;
}
