import sys, math
input = lambda: sys.stdin.readline()[:-1]
def MI(): return map(int, input().split())
inf = 10**18
sys.setrecursionlimit(10**7)  # Codeforcesでは350000程度に

def f(x):
    if x < 10: return 0
    res = 1
    while x:
        res *= x%10
        x //= 10
    return 1 + f(res)

print(f(int(input())))