#include<cstdio>

int n, x, a, b;

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

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

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

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

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