Samodelkin, Professor decided make by hand volumetric model bricks from matches, and use the matches for edges. Length of edges of every brick equally for one match.

For model’s construction of three bricks he uses 28 matches.

What least quantity of matches Samodelkin needs for construction of model with N bricks?

Every number of problems does not exceed `2'

Input

One number N is quantity of bricks.

Output

One number is quantity of matches.