#include <iostream>
using namespace std;
using ll = long long;

int main()
{
    int a, b, c, d, ans = 0;
    cin >> a >> b >> c >> d;
    while (1 + c < d && a > 0 && b >= c)
    {
        ans++;
        b -= c;
        a--;
    }
    cout << ans << endl;
}