#include<cstdio>

long long n, x, a, b;

int main()
{
    scanf("%lld %lld %lld %lld", &n, &x, &a, &b);

    long long max = 1;
    for (int i = 0; i < n - 1; i++) max *= 2;

    long long at = 0;
    long long hp = x;
    while (hp > 0) {
        hp -= a;
        at++;
    }

    long long re = 0;
    hp = x;
    while (hp < max) {
        hp += b;
        re++;
    }

    if (at > re) printf("%lld\n", re);
    else printf("%lld\n", at);
}