#include <bits/stdc++.h> using namespace std; int main() { int n,sum = 0,temp = 0; cin>>n; for(int i = 1;i <= n;i++) { temp = i; while(temp != 0) { int p = temp % 10; if(p == 1) { sum++; } temp /= 10; } } cout<<sum<<endl; return 0; }