visited = []

def isPrime(num):
    if num == 1:
        return False
    for i in range(2, int(num ** 0.5 + 1)): #???? where sqrt?
        if num % i == 0:
            return False
    return True

def recursive(num):
    s = str(num)
    if len(s) < 2:
        if isPrime(num):
            return 1
        return 0
    m = 0
    for i in range(len(s)):
        cur = int(s[:i] + s[i+1:])
        if cur in visited:
            continue
        visited.append(cur)
        if not isPrime(cur):
            continue
        m = max(recursive(cur), m)
    return m + 1

def main():
    n = int(input())
    if not isPrime(n):
        print(0)
        return
    print(recursive(n))


main()