Problem Statement
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 $2 \times M$ 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 $2 \times M$ bricks are possible? Write a program to find the answer. Since it can be extremely large, print the count modulo $10^9+7$.
Constraints
$1 \leq N \leq 3000$$1 \leq M \leq 3000$
Input
Input is given from Standard Input in the following format:
N M
Output
Print the count of the different possible sequences of colors of $2 \times M$ bricks that will be stacked, modulo $10^9+7$.
样例
2 3
56
1000 10
1048576
1000 3000
693347555
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