#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ll long long

typedef unsigned long long ull;
ull modmul(ull a, ull b, ull M) {
    ll ret = a * b - M * ull(1.L / M * a * b);
    return ret + M * (ret < 0) - M * (ret >= (ll)M);
}
ull modpow(ull b, ull e, ull mod) {
    ull ans = 1;
    for (; e; b = modmul(b, b, mod), e /= 2)
        if (e & 1) ans = modmul(ans, b, mod);
    return ans;
}
bool isPrime(ull n) {
    if (n <  2 || n % 6 % 4 != 1) return (n | 1) == 3;
    ull A[] = {2, 325, 9375, 28178, 450775, 9780504, 1795265022},
        s = __builtin_ctzll(n - 1), d = n >> s;
    for (ull a : A) {
        ull p = modpow(a%n, d, n), i = s;
        while (p != 1 && p !=  n - 1 && a % n && i--)
            p =  modmul(p, p, n);
        if (p != n-1 && i != s) return 0;
    }
    return 1;
}

int ans = 0;
void rec(int n, int cnt) {
    if (n == 0) return;
    // cout << n << "  " << cnt << " << " << isPrime(n) << endl;
    if (!isPrime(n)) return;
    ans = max(ans, cnt);

    int inc = 0;
    int ml = 1;
    while (n > 0) {
        int lst = n % 10;
        n /= 10;
        rec(n*ml + inc, cnt + 1);

        inc += (lst*ml);
        ml *= 10;
    }

}

int32_t main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    int n;
    cin >> n;
    rec(n, 1);
    cout << ans << '\n';

    return 0;
}