#include <bits/stdc++.h>
using namespace std;
int main(void){
    long long A,B,N,M,mc=0;cin >> A >> B >> N >> M;mc=min(A,B);
    if(B>A){
        if(B-A>M){
            int m=(B-A)/(M+1);
            mc=A+m;
        }
    }else if(A>B){
        if(A-B>N){
            int m=(A-B)/(N+1);
            mc=B+m;
        }
    }
    cout << mc << endl;
}