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.
num_books = int(input())

n = 1
sum_digits = 0
num_valid_numbers = 9

while True:
    if num_books > num_valid_numbers:
        sum_digits += (num_valid_numbers * n)
        num_books -= num_valid_numbers
        num_valid_numbers *= 10
        n += 1
    else:
        sum_digits += (num_books * n)
        break

print(sum_digits)
