#include <map>
#include <set>
#include <array>
#include <cmath>
#include <deque>
#include <bitset>
#include <random>
#include <string>
#include <vector>
#include <cassert>
#include <complex>
#include <iomanip>
#include <iostream>
#include <algorithm>
#include <unordered_map>
#include <unordered_set>

using namespace std;
#define int long long

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);

  int n, p;
  cin >> n >> p;

  int sumc = 0;
  for (int i = 0; i < n; ++i) {
    int c;
    cin >> c;

    if (c - 1 > 4 * p / (i + 1)) {
      cout << i << '\n';
      return 0;
    }

    if (p - sumc - __int128_t(i + 1) * (c - 1) < c) {
      cout << i << '\n';
      return 0;
    }

    sumc += c;
  }

  cout << n << '\n';
  
  return 0;
}