Problems

# Match’s model

# Match’s model

Professor Samodelkin decided to make a three-dimensional model of cubes from matches using matches for the edges of the cubes. The length of the edge of each cube is equal to one match. He used 28 matches to build a model of three cubes.

What is the smallest number of matches needed by Samodilkin to build a model of N cubes.

All numbers in this problem do not exceed 2·10^9.

#### Incoming data

One number N is the number of cubes.

#### Output data

The number of matches needed.

## Examples

Input example #1

1

Output example #1

12