#D10961. Piling Up
Piling Up
Piling Up
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.
Examples
Input
2 3
Output
56
Input
1000 10
Output
1048576
Input
1000 3000
Output
693347555
inputFormat
Input
Input is given from Standard Input in the following format:
N M
outputFormat
Output
Print the count of the different possible sequences of colors of 2 \times M bricks that will be stacked, modulo 10^9+7.
Examples
Input
2 3
Output
56
Input
1000 10
Output
1048576
Input
1000 3000
Output
693347555
样例
1000 3000
693347555