HZNUOJ

Tri Tiling

Tags:
Time Limit:  1 s      Memory Limit:   128 MB
Submission:4     AC:4     Score:99.81

Description

In how many ways can you tile a 3xn rectangle with 2x1 dominoes?

Here is a sample tiling of a 3x12 rectangle.

 

Input consists of several test cases followed by a line containing -1. Each test case is a line containing an integer 0 ≤ n ≤ 30. For each test case, output one integer number giving the number of possible tilings.

Samples

input
2 8 12 -1
output
3 153 2131