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

template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}

//INSERT ABOVE HERE
signed main(){
  Int n,x,a,b;
  cin>>n>>x>>a>>b;
  Int ans=(x+a-1)/a;
  Int y=(1LL<<(n-1))-x;
  chmin(ans,(y+b-1)/b);
  cout<<ans<<endl;
  return 0;
}