#include <cmath>
#include <iostream>
#include <limits>
#include <unordered_map>
#include <unordered_set>

using namespace std;

unordered_map<int, int> dp;

bool isPrime(int num) {
    if (num == 1) {
        return false;
    }

    if (num == 2) {
        return true;
    }

    if ((num & 1) == 0) {
        return false;
    }

    int s = static_cast<int>(sqrt(num));

    for (int div = 3; div <= s; div += 2) {
        if (num % div == 0)
            return false;
    }

    return true;
}

int removeNthDigit(int num, int digit) {
    if (digit == 0) {
        return num / 10;
    }

    int base = static_cast<int>(pow(10, digit));

    int right = num % base;
    int left = num / (base * 10);
    return left * base + right;
}

int countDigits(int num) {
    int digit = 0;
    int base = 1;

    for (int i = 0; i < 32; ++i) {
        if (num / base == 0) {
            break;
        }
        ++digit;
        base *= 10;
    }

    return digit;
}

int findMaxPrimes(int num) {
    if (num == 0) {
        return 0;
    }

    if (dp.find(num) != dp.end()) {
        return dp[num];
    }

    if (!isPrime(num)) {
        return 0;
    }

    int digits = countDigits(num);
    int best = 0;

    for (int i = 0; i < digits; ++i) {
        int withoutDigit = removeNthDigit(num, i);
        best = std::max(best, findMaxPrimes(withoutDigit));
    }

    dp[num] = best + 1;
    return best + 1;
}

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

    cout << findMaxPrimes(num) << endl;
}