n = int(input())

def is_prime(n):
    if n < 2:
        return False
    div = 2
    while div * div <= n:
        if n % div == 0:
            return False
        div += 1
    return True

curr = set()
if is_prime(n):
    curr.add(n)

ans = 0
while curr:
    ans += 1
    cand = set()
    for i in curr:
        if i < 10:
            continue
        istr = str(i)
        for j in range(len(istr)):
            cand.add(int(istr[:j] + istr[j+1:]))
    curr = {c for c in cand if is_prime(c)}

print(ans)