#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i = 0; i < n; i++)
using ll = long long;
int main() {
  ll 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;
}