#include <iostream>
#include <vector>
#include <unordered_set>
#include <string>
#include <math.h>

using namespace std;
unordered_set<int> set;

unordered_set<int> primeGenerate (int cap){

    vector<bool>isPrime(cap + 1, true);

    for (int i = 2; i < sqrt(cap); i++){
        if(!isPrime[i]) continue;

        for (int j = 2*i; j < cap; j+=i) {
            isPrime[j] = false;
        }
    }

    for (int i = 0; i < cap + 1; ++i) {
        if(isPrime[i]) {
            set.insert(i);
        }
    }
    return set;
}

int parseStringToNums(string num, int primesInRow, bool isFirst){
    int numToInt = stoi(num);

    if(set.find(numToInt) == set.end()){
        primesInRow++;
        if (num.length() == 1){
            return primesInRow;
        }
    } else{
        if(!isFirst) {
            return 0;
        }
    }

    int max_result = 0;
    for (int i = 0;  i < num.size(); i++){
        char new_string[num.size()];
        int new_idx = 0;
        for (int j = 0; j < num.size(); ++j) {
            if(i==j) continue;
            new_string[new_idx] = num[j];
            new_idx++;
        }
        max(max_result, parseStringToNums(new_string, primesInRow, false));
    }
    return max_result;
}

int main() {

    string num;
    cin >> num;

    int stringToNum = stoi(num);

    unordered_set<int> primes;

    primes = primeGenerate(stringToNum);

    int result = parseStringToNums(num, 0, true);

    cout << result << endl;
    
    return 0;
}