#include <bits/stdc++.h>
using namespace std;
using namespace std::chrono;
template <typename T>
void print(string name, vector<T>& v) {
  if (name.size()) cout << name << ": ";
  int s = (int)v.size();
  for (int i = (int)(0); i < (int)(s); ++i) cout << v[i] << " ";
  cout << endl;
}
template <typename T>
void print(vector<T>& v) {
  print("", v);
}
int main() {
  int test_cases = 1;
  ios::sync_with_stdio(false);
  for (int test_case = (int)(0); test_case < (int)(test_cases); ++test_case) {
    long long n, k;
    cin >> n >> k;
    vector<long long> id(n + 1);
    for (int i = (int)(1); i <= (int)(n); ++i) cin >> id[i];
    double delta = sqrt(1.0 + 8 * k);
    double p2 = (delta - 1) / 2;
    long long p = (long long)p2;
    long long j = k - p * (p + 1) / 2;
    if (j == 0) j = p;
    cout << id[j] << endl;
  }
  return 0;
}
