#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, k, a[100005];
  cin >> n >> k;
  for (int i = 1; i <= n; i++) cin >> a[i];
  long long cur = 1;
  while (true) {
    if (cur * (cur + 1) / 2 <= k)
      cur++;
    else
      break;
  }
  if (cur * (cur + 1) / 2 > k) cur--;
  if (k == cur * (cur + 1) / 2)
    cout << a[cur];
  else
    cout << a[k - cur * (cur + 1) / 2];
  return 0;
}
