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

#define rep(i, n) for(int i = 0;i < n;i++)
#define repr(i, n) for(int i = n;i >= 0;i--)
#define FOR(i, m, n) for(int i = m;i < n;i++)

int main(){
  long long int x,a,b,z=1;
  int n;
  cin>>n>>x>>a>>b;
  rep(i,n-1){
    z=z<<1;
  }
  //cout<<z<<endl;
  int s=0,t=0;
  while(z>x){
    z-=b;
    t++;
  }
  while(x>0){
    x-=a;
    s++;
  }
  //cout<<s<<t<<endl;
  cout<<min(s,t)<<endl;
  return 0;
}