#include <bits/stdc++.h>
using namespace std;
const int INF = 0x3f3f3f3f;
const double PI = acos(-1.0);
const int N = 100010;
vector<long long> sum;
int v[N];
int main(void) {
  int n;
  long long k;
  cin >> n >> k;
  for (int i = 0; i < n; i++) {
    scanf("%d", v + i);
  }
  sum.push_back(0);
  for (int i = 1; i <= n; i++) {
    sum.push_back(sum[i - 1] + (i * 1LL));
  }
  sum.push_back(LLONG_MAX);
  int q = upper_bound(sum.begin(), sum.end(), k) - sum.begin() - 1;
  if (k == sum[q]) {
    printf("%d\n", v[q - 1]);
  } else
    printf("%d\n", v[k - sum[q] - 1]);
  return 0;
}
