#include <bits/stdc++.h>
#include<iostream>
#include<map>
#include<vector>
#include <algorithm>
#include<math.h>
#include <iomanip>
#include<set>
#include <numeric>
#include<string>
using namespace std;


int main()
{
    long long a, b, n, m;
    cin >> a >> b >> n >> m;
    if (a == b) cout << a << endl;
    else if (a > b) cout << b + (a-b)/(n+1) << endl;
    else cout << a + (b-a)/(m+1) << endl;
}