#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int m, n, i, a, k, b, j = 0, l = 0, r = 0, c, ct = 0, pos = 0,
                                  neg = 0, flag = 0, temp = 0, x, y, space,
                                  maxi, ans = 0, ans2 = -100;
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  char ch;
  long long int emp[101] = {0}, lang[101] = {0};
  string st, st2, st3;
  vector<long long int> v, v2;
  vector<pair<long long int, long long int> > vp;
  queue<pair<long long int, long long int> > q;
  cin >> a >> b;
  for (i = 0; i < a; i++) {
    cin >> temp;
    v.push_back(temp);
  }
  temp = 1;
  flag = 1;
  while (1) {
    temp += flag;
    flag++;
    if (temp > b) {
      temp -= (flag - 1);
      break;
    }
  }
  cout << v[b - temp];
  return 0;
}
