#include <bits/stdc++.h>

using namespace std;

#define ll long long
unordered_map<int, bool> primes;

bool isPrime(int value){
    if (value <= 2) return false;
    if (value % 2 == 0) return false;
    if (value % 3 == 0) return false;

    if(primes.find(value) != primes.end()){
        return primes[value];
    }


    int sq = sqrt(value);

    for(int i = 3; i <= sq; i+=2){
        if(value % i == 0) return false;
    }

    return true;
};

int result = 0;

void rec(int prime, int cnt){
    if(!isPrime(prime)){
        primes[prime] = false;
        result = max(result, cnt);
        return;
    }
    cnt++;
    primes[prime] = true;

    auto stringPrime = to_string(prime);
    for(int toRemove = 0; toRemove < stringPrime.length(); toRemove++){
        auto cpy = stringPrime;
        cpy = cpy.erase(toRemove, 1);
        auto next = atoi(cpy.c_str());
        rec(next, cnt);
    }
}

int main(){
    int n;
    cin >> n;

    auto stringPrime = to_string(n);

    auto isPrimeStart = isPrime(n);
    for(int toRemove = 0; toRemove < stringPrime.length(); toRemove++){
        auto cpy = stringPrime;
        cpy.erase(toRemove, 1);
        auto next = atoi(cpy.c_str());
        rec(next, isPrimeStart);
    }

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