import itertools

packages = [6, 9, 20]
smaller = min(packages)
num = 1

count = 0
while count < smaller:
    n = 1
    while n * smaller < num:
        combinations = itertools.combinations_with_replacement(packages, n)
        for x in combinations:
            total = sum(x)
            if total == num:
                count += 1
                break
        else:
            n += 1
            continue
        break
    else:
        count = 0
    num += 1
print(num - 1 - smaller)