Ocenki

twos = int(input())
threes = int(input())
fours = int(input())


if 2 * (2 * twos + 3 * threes + 4 * fours) >= 7 * (twos + threes + fours):
    print(0)
else:
    l = 0
    r = twos + threes
    while r - l > 1:
        fives = l + (r - l) // 2
        if 2 * (2 * twos + 3 * threes + 4 * fours + 5 * fives) < 7 * (twos + threes + fours + fives):
            l = fives
        else:
            r = fives
    print(r)