/*
    No.804 野菜が苦手
    https://yukicoder.me/problems/no/804
*/
#include <bits/stdc++.h>
using namespace std;

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);

    int a, b, c, d;
    cin >> a >> b >> c >> d;

    int max_vege = 0;

    for (int vegetable = 0; vegetable <= a; vegetable++) {
        for (int meat = 0; meat <= b; meat++) {
            cerr << "vegetable, meat = " << vegetable << ", " << meat << endl;
            if (vegetable + meat <= d) {
                if (vegetable * c <= meat) {
                    max_vege = max(max_vege, vegetable);
                }
            }
        }
    }
    cout << max_vege << endl;
}