#include <bits/stdc++.h>
using namespace std;
    
int main(){
    int i,g,s,b,q,n,c = 0;
    cin>>n;
    for(i = 1;i <= n;i++){
        g = i % 10;
        s = i / 10 % 10;
        b = i / 100 % 10;
        q = i / 1000;
        if(g == 1){
            c++;
        }
        if(s == 1){
            c++;
        }
        if(b == 1){
            c++;
        }
        if(q == 1){
            c++;
        }
    }
    cout<<c<<endl;
}
/**************************************************************
	Problem: 1448
	User: linmiaoling
	Language: C++
	Result: Accepted
	Time:17 ms
	Memory:2072 kb
****************************************************************/