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