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 Input consists of several test cases followed by a line containing ‘-1’. Each test case is a line containing an integer 0 ≤ n ≤ 30. Output For each test case, output one integer number giving the number of possible tilings. Sample Input 2 8 12 -1 Sample Output 3 153 2131