#include <bits/stdc++.h>
using namespace std;
long long range[1000007];
long long arr[1000007];
long long n, k;
void limit() {
  long long sum = 1;
  range[1] = sum;
  for (long long i = 2; i <= n; i++) {
    range[i] = sum + i;
    sum += i;
  }
}
int main() {
  cin >> n >> k;
  limit();
  for (long long i = 1; i <= n; i++) {
    cin >> arr[i];
  }
  long long start = 0;
  for (long long i = 2; i <= n; i++) {
    if (k > range[i - 1] && k <= range[i]) {
      start = range[i - 1];
      break;
    }
  }
  long long res = arr[k - start];
  cout << res << endl;
}
