#include <iostream>
#include <cstdio>
using namespace std;

int main()
{
	freopen("bs.in","r",stdin);
	freopen("bs.out","w",stdout);
	int maxo,maxx;
	int counto,countx;
	while(cin>>counto>>countx>>maxo>>maxx)
	{
		if (counto>countx)
		{
			swap(counto,countx);
			swap(maxo,maxx);
		}
		//special
		if (maxo==0&&maxx==0)
		{
			cout<<0<<endl;
			continue;
		}
		if (maxo==0||maxx==0)
		{	
			cout<<min(maxo,counto)+min(maxx,countx);
			continue;
		}
		//usual
		if (counto==countx)
		{
			printf("%d\n",counto+countx);
			continue;
		}
		int groupo=counto,groupx=groupo+1;
		int eacho=counto/groupo,eachx=countx/groupx;
		int lefto=counto-eacho*groupo,leftx=groupx-eacho*groupx;
		int cano=(maxo-eacho)*groupo,canx=(maxx-eachx)*groupx;
		int re=eacho*groupo+eachx*groupx+
			min(cano,lefto)+min(canx,leftx);
		cout<<re<<endl;
	}
	return 0;
}