#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
using ll = long long;
using ld = long double;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    ll N,X,A,B; cin >> N >> X >> A >> B;
    ll ansA = (X + A - 1) / A;
    ll ansB = ((1LL << (N - 1)) - X + B - 1) / B;
    cout << min(ansA, ansB) << endl;
}