Competitions

# Simple Combinatorics

# Triangles

Mike likes to draw triangles, but he does it in an unusual way. First he draws an arbitrary triangle, then divides each side into **n** equal parts and draws through the partition points the lines parallel to sides of triangle. As a result he gets a number of triangles equal to each other. Help Mike to find the maximum number of identical triangles in his final picture.

#### Input

One integer **n** (**0** < **n** < **2** * `10`

).^{9}

#### Output

The maximum number of triangles equal to each other.

Input example #1

2

Output example #1

4