#include <iostream>

using lint = long long;

void solve() {
    int n;
    lint x, a, b;
    std::cin >> n >> x >> a >> b;

    lint down = x,
         up = (1LL << (n - 1)) - x;
    std::cout << std::min((down + a - 1) / a,
                          (up + b - 1) / b)
              << std::endl;
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}