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