Aw, Ab = map(int, raw_input().split())
Bw, Bb = map(int, raw_input().split())
C, D = map(int, raw_input().split())


if C <= Ab:
    Ab = Ab - C
    Bb = Bb + C
else:
    Aw = Aw - (C - Ab)
    Bw = Bw + (C - Ab)
    Bb = Bb + Ab
    Ab = Ab - Ab
    
#print Aw, Ab, Bw, Bb

if D <= Bw:
    Bw = Bw - D
    Aw = Aw + D
else:
    Bb = Bb - (D - Bw)
    Ab = Ab + (D - Bw)
    Bw = Bw - Bw
    Aw = Aw + Bw


#print Aw, Ab, Bw, Bb

print Aw