import math

primes = []


def isPrime(n):
    if n == 1:
        return False
    for i in range(2,math.floor(math.sqrt(n))+1):
        if n % i == 0:
            return False
    return True

n = input()

def rec(n, max):
    wasPrime = False
    better = False
    newMax = max
    for i in range(len(n)):
        new = n[:i] + n[i+1:]
        if isPrime(int(new)):
            new = str(int(new))
            wasPrime = True
            if (len(new) > 1):
                res = rec(new, newMax + 1)
                if res > max:
                    max = res
                    better = True
    if wasPrime:
        if better:
            return max
        else:
            return max+1
    else:
        return 0

if isPrime(int(n)):
    ret = rec(n, 1)
    print(max(ret, 1))
else:
    print(0)