#include <bits/stdc++.h>
using namespace std;
int const siz = 1e9, bound = 7e5, mod = siz + 9;
long long const oo = 1e18;
int aa[bound];
int main() {
  int n, k;
  scanf("%d", &n), scanf("%d", &k);
  for (int(i) = 0; (i) < (n); (i)++) scanf("%d", &aa[i]);
  int l = 0, r = n, mid, rob;
  while (l <= r) {
    mid = (l + r) >> 1;
    if ((long long)mid * (mid + 1) / 2 >= k) {
      rob = mid;
      r = mid - 1;
    } else
      l = mid + 1;
  }
  long long cur = (long long)(rob - 1) * rob / 2 + 1;
  int idn = 0;
  while (cur < k) {
    cur++;
    idn++;
  }
  printf("%d\n", aa[idn]);
  return 0;
}
