Aw,Ab = map(int,raw_input().split())
Bw,Bb = map(int,raw_input().split())
C,D = map(int,raw_input().split())
if Ab < C:
	Aw -= (C - Ab)
	Bw += (C - Ab)
	Bb += Ab
	Ab = 0
else:
	Ab -= C
	Bb += C
Aw += min(Bw,D)
print Aw