Vasya likes to take a walk in unusual places. One time he stumbled across a beautiful infinite road and, of course, decided to take a walk. Vasya moves along the road with constant speed and passes by several lampposts every hour. It’s notable that exactly at the end of each hour Vasya passed by a lamppost. Let’s call the lampost that Vasya passed by at the end of i-th hour the i-th interesting lamppost.
Lampposts are distributed evenly along the road, and each lamppost has a number assigned to it. Numbers of lampposts are successive integers. Vasya wrote down in his notebook all numbers of interesting lampposts without changing his pace.
A gust of wind ripped out a page that had the number of the k-th interesting lamppost. Vasya wants to find out that number, but he can’t remember his speed on the walk along the infinite road. Help Vasya to restore his notes.
The first and only line contains one integer k (0 ≤ k ≤ 105) — end of k-th hour.
Output the number of the k-th interesting lamppost.
Problem Author: Denis Avriskin