#include <bits/stdc++.h>
int main() {
  long long n, k, a[100001], i, s, c, d;
  while (~scanf("%lld%lld", &n, &k)) {
    s = 0;
    c = 0;
    for (i = 1; i <= n; i++) {
      scanf("%lld", &a[i]);
    }
    while (s < k) {
      c++;
      s += c;
    }
    s = s - c;
    d = k - s;
    printf("%lld\n", a[d]);
  }
}
