/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2021.03.31 21:41:41
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

int main() {
    ll a,b,n,m;cin >> a >> b >> n >> m;
    ll k = min(a,b);
    a -= k;
    b -= k;
    if (a == 0) {
        cout << max(b/(m+1),b-(b/(m+1)+1)*m) + k << endl;
    }
    else {
        cout << max(a/(n+1),a-(a/(n+1)+1)*n) + k << endl;
    }
    return 0;
}