#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#include <list>
#include <atcoder/all>
#define popcount __builtin_popcount
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef pair<int, int> P;

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