def collatz(n):
    answer = 0
    while n > 1:
        if n % 2 == 0:
            n = n // 2
            answer += 1
        elif n % 2 != 0:
            n = n * 3 + 1
            answer += 1
        if answer > 500:
            return -1
        
    return answer
        
n = 6
ret = collatz(n)
print(ret)