#include <bits/stdc++.h>
using namespace std;
int id[100100];
int n;
unsigned long long k;
int main() {
  ios ::sync_with_stdio(false);
  cin.tie(0);
  cin >> n >> k;
  for (int i = 1; i <= n; i++) cin >> id[i];
  unsigned long long x = 2 * k;
  unsigned long long h = (unsigned long long)sqrt(x);
  if (h * (h + 1) / 2 > k) h--;
  k -= (h * (h + 1) / 2);
  if (!k)
    cout << id[h];
  else
    cout << id[k];
  return 0;
}
