#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")

#define fi first
#define se second
#define int long long
#define vec vector


using namespace std;

unordered_map<int, int> used;
unordered_map<int, int> cnt;


int rec(int n)
{
    if(used[n]==1)
    {
        return cnt[n];
    }
    bool flag = true;

    if(n == 1 || n == 0)
    {
        cnt[n] = 0;
        used[n] = 1;
        return 0;
    }
    for(int i = 2; i<sqrt(n)+1; i++)
    {
        if(n % i == 0)
        {
            flag = false;
        }
    }
    if(!flag){
        cnt[n] = 0;
        used[n] = 1;
        return 0;
    }
    if(n<10){
        cnt[n] = 0;
        if(flag)
            cnt[n]++;
        used[n] = 1;
        return cnt[n];
    }

    int ans = 0;
    int d = 1;
    int ost = 0;
    int alt = n;
    while(n > 0)
    {
        int ost1 = (n % 10)*d+ost;
        n/=10;
        int a = n*d + ost;
        // cout << alt<< " "<<a <<"\n";
        int nv=0;
        if(flag)
            nv++;
        ans = max(ans, rec(a)+nv);
        ost = ost1;
        d*=10;
    }

    cnt[alt] = ans;
    used[alt] = 1;

    return ans;


}

void solve()
{
    int n;
    cin>>n;
    int ans = rec(n);
    cout << ans;
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int tests = 1;
    while(tests--)
    {
        solve();
    }

}