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.
import math
def digit(n):
    return math.floor(math.log(n, 10)+1)
    
n=int(input())
sum=1
for i in range(2,n+1):
    sum=sum+digit(i)
print(sum)
        
