#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using ull = unsigned long long;
#define cerr if(0) cout

map<ll, int> bc;

bool is_prime(ll k) {
	if(k < 2) return false;
	if(k == 2) return true;
	if(k % 2 == 0) return false;
	for(ll i = 3; i*i <= k; i += 2) {
		if(k % i == 0) return false;
	}
	return true;
}

int nom(ll k) {
	cerr << "k: " << k << '\n';
	if(bc.contains(k)) return bc[k];
	if(!is_prime(k)) {
		bc[k] = 0;
		return 0;
	}
	int bst = 1;
	for(ll b = 1; b < 10*k; b*= 10) {
		ll tr = k % b;
		ll hd = (k / (b*10));
		ll nw = tr + (hd * b);
		if(nw == k) break;
		if(is_prime(nw)) {

		}
		bst = max(bst, 1 + nom(nw));
	}
	bc[k] = bst;
	cerr << "k: " << k << '\n';
	cerr << bst << '\n';
	return bst;
}

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);

	int n;
	cin >> n;

	cout << nom(n) << '\n';

	return 0;
}