#include<iostream>
using namespace std;
int main(void)
{
	/*Aw-(C-Ab)のこる
		C-Abこ移動して
	(Bw+C-Ab)><Dこ移動できる*/
	int aw, ab, bw, bb, c, d, ans=0,p;
	cin >> aw >> ab >> bw >> bb >> c >> d;

	if (c >= ab)p = c - ab; else p = 0;
	if (bw + p >= d)ans = aw -p + d;
	else ans = aw + bw;

	cout << ans << endl;
	return 0;
}