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