#include <iostream>
#include <vector>
#include <set>
#include <cmath>

using namespace std;

bool is_prime(int num) {
    if (num == 1) return false;
    if (num == 2) return true;

    for (int i = 3; i < std::sqrt(num); i += 2)
        if (num % i == 0)
            return false;
    return true;
}

void rec ( string a, int& b, int c ){

    if ( !is_prime(stoi( a ) ) ){
        return;
    }

    set< int > tmp;

    c = c + is_prime( stoi( a ) );

    if ( a.length() == 1 ){
        if ( c > b ){
            b = c;
        }
        return;
    }

    for ( int i = 0; i < a.length(); i++ ){
        string tmpstr;
        for ( int x = 0; x < a.length(); x++ ){
            if  ( x != i ){
                tmpstr.push_back( a[ x ] );
            }
        }
        tmp.insert(stoi(tmpstr) );
    }
    for ( auto x : tmp ){
        rec(to_string(x), b, c );
    }
}




int main() {
    int a, b = 0;
    cin >> a;
    rec (to_string( a ), b, 0 );
    cout << b << endl;

    return 0;
}