#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n;
  long long int k;
  cin >> n;
  cin >> k;
  int* all = new int[n];
  for (long long int i = 1; i <= n; i++) scanf("%d", &all[i]);
  long long int robot = 1;
  long long int cur = 1;
  while (cur < k) {
    cur = (robot + 1) * (robot + 2) / 2;
    robot++;
  }
  cur = robot * (robot - 1) / 2;
  printf("%d", all[k - cur]);
  return 0;
}
