// WA? int でオーバーフローする?

#include <iostream>
#include <cassert>
#include <cmath>
using namespace std;
int main(){
  int n,x,a,b;
  cin >> n >> x >> a >> b;
  assert( 2<= n && n<=32 );
  assert( 1 <= x && x < (1LL<<(n-1)) );
  assert( 1 <= a && a < (1LL<<(n-1)) );
  assert( 1 <= b && b < (1LL<<(n-1)) );

  int ans = min( ((x + a-1)/a), ( ((1<<(n-1)) - x + b-1) / b) );
  cout << ans << endl;

  return 0;
}