def main():
    Aw, Ab = map(int, input().split())
    Bw, Bb = map(int, input().split())
    C, D = map(int, input().split())

    if Aw < C:
        Bw += Aw
        Aw = 0
    else:
        Bw += C
        Aw -= C

    if Bw < D:
        print(Aw + Bw)
    else:
        print(Aw + D)


if __name__ == '__main__':
    main()