#include <bits/stdc++.h>
using namespace std;

int main(){
    long long n, x, a, b;
    cin >> n >> x >> a >> b;
    long long overflow = 1LL << (n - 1);
    long long sa = (overflow - x - 1LL) / b + 1LL;
    long long sb = (x - 1LL) / a + 1LL;
    cout << min(sa, sb) << endl;
    return 0;
}