#include <bits/stdc++.h>
using namespace std;
long long b[100001];
long long k;
int n;
int main() {
  cin >> n >> k;
  for (int i = 1; i <= n; i++) cin >> b[i];
  long long now = 0, cas = 1;
  while (now < k) {
    now += cas;
    cas++;
  }
  cout << b[k - (now - cas + 2) + 1] << endl;
}
