#include <stdio.h>
#include <math.h>

int main(void)
{
    long n,x,a,b;
    scanf("%ld%ld%ld%ld",&n,&x,&a,&b);
    if((x+a-1)/a>((long)pow(2,n-1)-2-x+b)/b)printf("%ld",((long)pow(2,n-1)-1-x+b)/b);
    else printf("%ld",(x+a-1)/a);
    return 0;
}