#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: admin
	Language: C++
	Result: Accepted
	Time:20 ms
	Memory:2072 kb
****************************************************************/