15

#https://inf-ege.sdamgia.ru/problem?id=19067
for a in range(100):
    flag = True #подходит ли a
    for x in range(100):
        for y in range(100):
            if not ((x + 2 * y < a) or (y > x) or (x > 30)):
                flag = False
    if flag:
        print(a)
        break