e-olymp
Problems

Gardener-painter

Gardener-painter

prb17

Gardener has to paint trees after planting. He has paint of three colour: white, blue and orange.

How many ways he can paint of N trees, if not any two the same colours can be side by side?

Input

The quantity of trees is N (1N50).

Output

The quantity of ways of paint.

Time limit 1 second
Memory limit 64 MiB
Input example #1
3
Output example #1
12