#include<bits/stdc++.h>
using namespace std;
#define int long long
int a = 1e9 + 1;

signed main(){
	int n;
	cin >> n;
	int b = n / a;

	if(a * b <= n){
		if(b < 10){
		cout << b << endl;
			return 0;
		}
		b /= 10;
		b += 9;
		cout << b << endl;
	}else{
		if(b < 10){
			cout << b << endl;
			return 0;
		}
		b /= 10;
		b += 8;
		cout << b << endl;
	}
}