A = input()
B = input()
CD = input()

Aw,Ab = A.split()
Bw,Bb = B.split()
C,D = CD.split()

Aw = int(Aw)
Ab = int(Ab)
Bw = int(Bw)
Bb = int(Bb)
C = int(C)
D = int(D)

if Ab - C < 0:
    Aw = Aw + (Ab - C)
    Bw = Bw + (C - Ab)
if D >= Bw:
    Aw = Aw + Bw
else:
    Aw = Aw + D

print(str(Aw))