Problems

Matches

What is the minimum number of matches necessary to pit on the plane n squares with a side in one match? Matches can not be broken and put on each other. The vertices of the squares should be the points where the ends of the matches meet, and the sides are matches themselves.

Write a program that by the number of squares n to be constructed, finds the minimum number of matches required for this.

Input

One integer n (1n109).

Output

Print the minimum number of matches required to construct n squares.

Time limit 1 second
Memory limit 128 MiB
Input example #1
4

Output example #1
12

Author Andrey Stasyuk
Source 2005 XVIII All-Ukrainian Informatics Olympiad, Rovno, April 10 - 16, Round 1