#include <bits/stdc++.h>
#include <cmath>

using namespace std;

bool is_prime(size_t s) {
    if (s <= 1)
        return false;
    for (int i = 2; i < ::sqrt(s) + 1; i++) {
        if (s % i == 0)
            return false;
    }
    return true;
}

size_t max (set<size_t> a){
    size_t ans = 0;
    for (size_t i : a){
        if (i > ans)
            ans = i;
    }
    return ans;
}

size_t count(size_t s) {
    if (s == 0)
        return 0;
    set<size_t> ans;
    for (size_t i = 0, copy = s; copy > 0; i++, copy /= 10) {
        size_t ss = s;
        ss = ss / (size_t)pow(10, i + 1) * (size_t)pow(10, i) + ss % (size_t)pow(10, i);
        if (is_prime(ss))
            ans.insert(1 + count(ss));
    }
    return max(ans);
}

int main() {
    size_t s;
    cin >> s;
    if (!is_prime(s))
        cout << 0;
    else
        cout << (count(s) + 1);

    return 0;
}