#pragma GCC optimize("O0")
#include <iostream>
using namespace std;
using ll=long long;

int main(){
  ll N;
  cin>>N;
  ll x=N;
  ll ans=0;
  while(x>=10){
    ll t=1;
    while(x>0){
      t*=x%10;
      x/=10;
    }
    x=t;
    ans++;
  }
  cout<<ans<<endl;
}