#include<bits/stdc++.h>
#define ll long long
#define ios ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#pragma GCC optimize("O3","unroll-loops")
#pragma GCC optimize("Ofast")
using namespace std;
ll kt(ll n)
{
    ll s=1;
    while(n>0)
    {
        s*=(n%10);
        n/=10;
    }
    return s;
}
ll tk(ll n)
{
    ios
    ll d=0;
    while(n>=10)
    {
        n=kt(n);
        d++;
    }
    return d;
}

int main() {
    ll n;
    cin>>n;
    cout<<tk(n);
    return 0;
}