#include <bits/stdc++.h>
using namespace std;

int main()
{
	long long A, B, N, M;
	cin >> A >> B >> N >> M;

	long long ans = A;
	if( A < B ) ans = A + (B - A) / (M + 1);
	if( A > B ) ans = B + (A - B) / (N + 1);

	cout << ans << endl;
}