#include <bits/stdc++.h>
using namespace std;
template <class T>
string tostring(T x) {
  ostringstream sout;
  sout << x;
  return sout.str();
}
template <class T>
int toint(T s) {
  int v;
  istringstream sin(tostring(s));
  sin >> v;
  return v;
}
vector<string> split(string sentence) {
  istringstream iss(sentence);
  vector<string> tokens;
  copy(istream_iterator<string>(iss), istream_iterator<string>(),
       back_inserter<vector<string> >(tokens));
  return tokens;
}
string conversion(int a, int b) {
  string cambio;
  int suma = 0;
  int coci = a;
  while (coci > 0) {
    cambio += tostring(coci % b);
    coci = coci / b;
  }
  return string(cambio.rbegin(), cambio.rend());
}
int GCD(int a, int b) {
  if (a % b == 0)
    return b;
  else
    return GCD(b, a % b);
}
int main() {
  int n, k;
  cin >> n >> k;
  vector<int> yay;
  for (int a = 0; a < n; a++) {
    int aux;
    cin >> aux;
    yay.push_back(aux);
  }
  int triangle = 0, num = 0;
  while (num < k) {
    triangle++;
    num += triangle;
  }
  num -= triangle;
  cout << yay[k - (num + 1)];
  return 0;
}
