#include <iostream>
using namespace std;
int main(int argc, char* argv[])
{
	int Aw,Ab;
	int Bw,Bb;
	int C,D;
	cin>>Aw>>Ab;
	cin>>Bw>>Bb;
	cin>>C>>D;
	if (Ab>=C){
		Ab-=C;
		Bb+=C;
	}else{
		Bb+=Ab;
		Bw+=C-Ab;
		Aw-=C-Ab;
		Ab=0;


	}
	if (Bw>=D){
		Bw-=D;
		Aw+=D;
	}else{
		Aw+=Bw;
		Ab+=D-Bw;
		Bw=0;
	}
	cout<<Aw<<endl;
	return 0;
}