#include <bits/stdc++.h>
using namespace std;

template <typename T>
T gcd(T x, T y)
{
    if (y == 0)
        return x;
    return gcd(y, x % y);
}

template <typename T>
T lcm(T x, T y)
{
    if (x == 0 || y == 0)
        return 0;
    return x / gcd(x, y) * y;
}

int main()
{
    int N;
    cin >> N;
    int X;
    cin >> X;
    int A;
    cin >> A;
    int B;
    cin >> B;
    int ans1 = X / A;
    if (X % A != 0)
        ans1++;
    int ans2 = (pow(2, N - 1) - X) / B;

    if ((int)(pow(2, N - 1) - X) % B != 0)
        ans2++;

    cout << min(ans1, ans2) << endl;
}