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

void no_1446(void) {
    long long a, b, n, m;
    cin >> a >> b >> n >> m;

    long long ans = min(a, b);
    a -= ans;
    b -= ans;
    if (a != 0) {
        long long a_div = a / n;
        long long a_remain = a % n;
        if(a_remain==0){
            a_div--;
            a_remain = n;
        }
        ans += min(a_div, a_remain);
    } else if(b!=0){
        long long b_div = b / m;
        long long b_remain = b % m;
        if(b_remain==0){
            b_div--;
            b_remain = m;
        }
        ans += min(b_div, b_remain);
    }
    cout << ans << endl;
}

int main(void) {
    no_1446();
    return 0;
}