#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, k;
  while (~scanf("%lld %lld", &n, &k)) {
    long long i = 1;
    while (i * (i + 1) / 2 <= k) ++i;
    --i;
    int rest = k - i * (i + 1) / 2;
    int pos;
    if (rest == 0)
      pos = i;
    else
      pos = rest;
    int ans;
    for (int i = 1; i <= n; ++i) {
      scanf("%d", &rest);
      if (i == pos) ans = rest;
    }
    printf("%d\n", ans);
  }
  return 0;
}
