#include<cstdio>
int main(void) {
unsigned int n,x,a,b;
scanf("%d%d%d%d",&n,&x,&a,&b);
unsigned int A=(x+a-1)/a;
unsigned int B=((1UL << (n-1))+b-1-x)/b;
printf("%d\n", A<B ? A : B);
}