def main():
    A_w, A_b = map(int, input().split())
    B_w, B_b = map(int, input().split())
    C, D = map(int, input().split())

    minus = max(0, C - A_b)
    plus = min(B_w+minus, D)
    print(A_w - minus + plus)


if __name__ == "__main__":
    main()