#include<bits/stdc++.h>
using namespace std;

#define ll long long
ll n;
ll ans=0;

ll col(ll x){
	ll y=0;
	while(x){
		y=max(y,x%10);
		if(y==9){
			return y;
		}
		x/=10;
	}
	return y;
}

int main(){
	
	freopen("countdown.in","r",stdin);
	freopen("countdown.out","w",stdout);
	
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	
	cin>>n;
	
	while(n){
		ll u=col(n);
		n-=u;
		ans++;
	}
	
	cout<<ans;
	
	return 0;
}