Joisino has a lot of red and blue bricks and a large box.
She will build a tower of these bricks in the following manner.
First, she will pick a total of N bricks and put them into the box.
Here, there may be any number of bricks of each color in the box, as long as there are N bricks in total.
Particularly, there may be zero red bricks or zero blue bricks.
Then, she will repeat an operation M times, which consists of the following three steps:
- Take out an arbitrary brick from the box.
- Put one red brick and one blue brick into the box.
- Take out another arbitrary brick from the box.
After the M operations, Joisino will build a tower by stacking the 2 × M bricks removed from the box, in the order they are taken out.
She is interested in the following question: how many different sequences of colors of these 2 × M bricks are possible?
Write a program to find the answer.
Since it can be extremely large, print the count modulo 109+7.
- 1 ≤ N ≤ 3000
- 1 ≤ M ≤ 3000
Subtask 1 (10%): 1 ≤ N, M ≤ 10
Subtask 2 (30%): 1 ≤ N, M ≤ 100
Subtask 3 (60%): No additional constraints
Subtask 4 (0%): Sample
Input is given from Standard Input in the following format:
Print the count of the different possible sequences of colors of 2 × M bricks that will be stacked, modulo 109+7.
Sample Input 1
Sample Output 1
A total of six bricks will be removed from the box. The only impossible sequences of colors of these bricks are the ones where the colors of the second, third, fourth and fifth bricks are all the same. Therefore, there are 26 - 2 × 2 × 2 = 56 possible sequences of colors.
Sample Input 2
Sample Output 2
Sample Input 3
Sample Output 3