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