#include<iostream>
using namespace std;
main(){
	int a1,a2,b1,b2,c,d;cin>>a1>>a2>>b1>>b2>>c>>d;
	b1+=c-a2<0?0:c-a2;a1-=c-a2<0?0:c-a2;
	cout<<a1+(b1<d?b1:d)<<endl;
}