#include <iostream>
#include<utility>
#include <vector>
#include <map>
#include<string>
#include<queue>
#include<math.h>
#define pb push_back
#define all(x) begin(x),end(x)
#define gall(x) begin(x),end(x),greater<>()
#define ll long long
#define P pair<int,int>
#define lP pair<ll,ll>
#include <iostream>
#include <vector>
using namespace std;
int main() {
    ll n;
    cin>>n;
    int ans=0;
    for(int i=1;i<=100000;i++){
        string t=to_string(i);
        string s=t+t+t;
        if(n>=stoll(s)) ans++;
    }
    cout<<ans<<endl;
    return 0;
}