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 20K

Acceptance rate 27%