#include <bits/stdc++.h>
using namespace std;
int N, K;
int id[100001];
int sem;
int main() {
  if (fopen("cf670b.in", "r")) {
    freopen("cf670b.in", "r", stdin);
    freopen("cf670b.out", "w", stdout);
  }
  cin >> N >> K;
  for (int i = 0; i < N; i++) {
    cin >> id[i];
  }
  if (K == 1) {
    cout << id[0] << '\n';
    return 0;
  }
  for (int i = 0; i < N; i++) {
    sem += i + 1;
    if (sem + (i + 2) >= K) {
      cout << id[K - sem - 1] << '\n';
      return 0;
    }
  }
}
