#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
using namespace std;
int main(){
	long long n,cnt=0;
	cin>>n;
	while(n){
		n=n-(n/10+n%10);
		++cnt;
	}
	cout<<cnt;
	return 0;
}

  只过1个测试点