#include <bits/stdc++.h>
using namespace std;
int main() {
  {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
  };
  long long n, k;
  cin >> n >> k;
  vector<long long> v(n);
  for (long long i = (long long)0; i <= (long long)n - 1; i++) cin >> v[i];
  long long cnt = 1, ans = 0;
  while (ans + cnt < k) {
    ans += cnt;
    cnt++;
  }
  long long temp = k - ans - 1;
  cout << v[temp] << endl;
  return 0;
}
