#include <bits/stdc++.h>
using namespace std;
template <typename T> bool chmax(T &u, const T z) { if (u < z) {u = z; return true;} else return false; }
template <typename T> bool chmin(T &u, const T z) { if (u > z) {u = z; return true;} else return false; }
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define ll long long 
long long mod=998244353;
int main(){
	ll n,kotae=0;
	cin>>n;
	if(n<100){
	  kotae=n/3-3;
	}else if(n<=300){
		kotae=31;
	}else{
		n/=100;
		kotae=9;
		while(n>=10){
			n/=10;
			if(n>=10){
				kotae*=10;
				kotae+=9;
			}else{
				kotae+=9;
			}
		}
		kotae+=30;
	}
	cout<<kotae<<endl;
	return 0;
}