# -*- coding:utf-8 -*-

if __name__ == "__main__":
	aw,ab = map(int,raw_input().split())
	bw,bb = map(int,raw_input().split())
	c,d = map(int,raw_input().split())
	temp = ab - c
	if temp < 0:
		aw = aw + temp
		bw = bw - temp
	temp = bw - d
	if temp < 0:
		aw = aw + bw
	else:
		aw = aw + d
	print aw