#include<iostream>
#include<cstdio>
#include<cstring>
#include<map>
#include<cmath>
#include<queue>
#include<algorithm>
#include<vector>
using namespace std;
int s[3],cnt=0,n,xiao[3];
int cmp (int a,int b)
{

	return a>b;
}
int main()
{
   ios::sync_with_stdio(0);
   cin>>n;
   s[1]=n/100;
   s[2]=n%100/10;
   s[3]=n%10;
   while(s[1]==4&&s[2]==9&&s[3]==5);
   {
     
	 sort(s,s+3,cmp);
	 xiao[1]=s[3];
	 xiao[2]=s[2];
	 xiao[3]=s[1];
	 s[1]=s[1]-xiao[1];
	 s[2]=s[2];
	 s[3]=s[3]-xiao[3];
    cnt++;
   } 
   cout<<cnt<<endl;
}