#include <stdio.h>

int main() {
    unsigned int n,x,a,b;
    scanf("%u\n%u\n%u\n%u",&n,&x,&a,&b);
    int atk= (x/a) + ((x%a==0) ? 0 : 1);
    int heal=(((1<<(n-1))-x)/b) + ((((1<<(n-1))-x)%b==0)?0:1);
    printf("%d\n",(atk>heal)?heal:atk);
}