Page numbering
Very easy
Execution time limit is 1 second
Runtime memory usage limit is 128 megabytes
For numbering m pages in the book n digits were used. By given n output the corresponding m or 0 if there is no solution. Numbering starts from first page.
Input
The only number n. The book contains no more than 7000 pages.
Output
Print the number of pages in the book.
Examples
Input #1
Answer #1
Submissions 21K
Acceptance rate 27%