In how many ways can you tile a 3×n rectangle with 2×1 dominoes?

Here is a sample tiling of a 3×12 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.

Example

Input:
2
8
12
-1

Output:
3
153
2131