Vanya got an important task — he should enumerate books in the library and label each book with its number. Each of the *n* books should be assigned with a number from 1 to *n*. Naturally, distinct books should be assigned distinct numbers.

Vanya wants to know how many digits he will have to write down as he labels the books.
The first line contains integer *n* (1 ≤ *n* ≤ 10<sup class="upper-index">9</sup>) — the number of books in the library.
#include <bits/stdc++.h>
#define ll long long
using namespace std;
int main()
{
  ll n;
  cin>>n;
  ll sum=0;
  for(int i=1;i<=n;i*=10)
  {
      sum+=(n-i +1);
  }
  cout<<sum<<"\n";
}
