#include<iostream>
using namespace std;
long A,B,N,M;
main()
{
	cin>>A>>B>>N>>M;
	if(A<=B)
	{
		long ans=A;
		B-=A;
		ans+=B/=M+1;
		cout<<ans<<endl;
	}
	else
	{
		long ans=B;
		A-=B;
		ans+=A/=N+1;
		cout<<ans<<endl;
	}
}