#include <bits/stdc++.h>

using namespace std;

map<string, int> res;

int run(string s){

	while(s[0] == '0'){

		s.erase(s.begin());
	}

	if(s.size() == 0){

		return 0;
	}

	if(res.count(s)){

		return res[s];
	}

	int num = atoi(s.c_str());

	bool prime = true;

	if(num == 1){

		prime = false;
	}

	for(int i = 2; i*i<=num; ++i){

		if(num%i == 0){

			prime = false;
		}
	}

	if(!prime){

		return res[s] = 0;
	}

	int _max = 0;

	for(int i = 0; i<(int)s.size(); ++i){

		string news = s;
		news.erase(i, 1);
		_max = max(_max, run(news));
	}

	return res[s] = _max+1;
}
int main(){


	string s;
	cin >> s;

	cout << run(s) << "\n";

}