def isPrime(num):
    if (num == 0 or num == 1): return False
    if (num == 2 or num == 3): return True
    if (num % 2 == 0): return False
    i = 3
    while (i*i <= num+3):
        if (num % i == 0): return False
        i+=2
    return True


num = int(input())
rez = int(isPrime(num))
while (num > 9):
    numS = str(num)
    numS = numS[1:]
    num = int(numS)
    rez += int(isPrime(num))
print(rez)