#include <bits/stdc++.h>
using namespace std;
long long unsigned seq[100005], arr[100005];
long long unsigned solve(int ends, long long unsigned k) {
  int n = ends;
  int beg = 0;
  while (beg <= ends) {
    int mid = (beg + ends) / 2;
    if (seq[mid] == k)
      return arr[mid];
    else if (seq[mid] > k)
      ends = mid - 1;
    else
      beg = mid + 1;
  }
  return arr[k - seq[ends]];
}
int main() {
  int n;
  long long unsigned k;
  cin >> n >> k;
  seq[0] = 0;
  for (int i = 1; i <= n; i++) {
    cin >> arr[i];
    seq[i] = i + seq[i - 1];
  }
  cout << solve(n, k) << endl;
  return 0;
}
