You are given two integers n and m. Calculate the number of pairs of arrays (a, b) such that:

  * the length of both arrays is equal to m; 
  * each element of each array is an integer between 1 and n (inclusive); 
  * a_i ≤ b_i for any index i from 1 to m; 
  * array a is sorted in non-descending order; 
  * array b is sorted in non-ascending order. 



As the result can be very large, you should print it modulo 10^9+7.

Input

The only line contains two integers n and m (1 ≤ n ≤ 1000, 1 ≤ m ≤ 10).

Output

Print one integer – the number of arrays a and b satisfying the conditions described above modulo 10^9+7.

Examples

Input


2 2


Output


5


Input


10 1


Output


55


Input


723 9


Output


157557417

Note

In the first test there are 5 suitable arrays: 

  * a = [1, 1], b = [2, 2]; 
  * a = [1, 2], b = [2, 2]; 
  * a = [2, 2], b = [2, 2]; 
  * a = [1, 1], b = [2, 1]; 
  * a = [1, 1], b = [1, 1]. 
from sys import stdin, stdout
from sys import maxsize
input = stdin.readline
# def print(n):
#    stdout.write(str(n)+'\n')

val = 10**9+7


def solve():
    pass


def fact(a, b):
    ans = 1
    for i in range(b+1, a+1):
        ans *= i
        ans % val
    return ans % val


test = 1
# test = int(input().strip())
for t in range(0, test):
    # n = int(input().strip())
    # s = list(input().strip())                                                        # String Input, converted to mutable list.
    n, m = list(map(int, input().strip().split()))
    a = 2*m+n-1
    b = max(2*m, n-1)
    print((fact(a, b)*pow(fact(a-b, 1), val-2, val)) % val)
    # arr = [int(x) for x in input().strip().split()]
    # brr = [list(map(int,input().strip().split())) for i in range(rows)]              # 2D array row-wise input
    ans = solve()


'''
rows, cols = (5, 5)
arr = [[0]*cols for j in range(rows)]                                         # 2D array initialization
b=input().strip().split()                                                             # list created by spliting about spaces
brr = [[int(b[cols*i+j]) for j in range(cols)] for i in range(rows)]          # 2D array Linear Input
rows,cols=len(brr),len(brr[0])                                                # no of rows/cols for 2D array
arr.sort(key = lambda x : x[1])                                               # sort list of tuples by 2nd element, Default priority - 1st Element then 2nd Element
s=set()                                                                       # empty set
a=maxsize                                                                     # initializing infinity
b=-maxsize                                                                    # initializing -infinity
mapped=list(map(function,input))                                              # to apply function to list element-wise
try:                                                                          # Error handling
    #code 1
except:                                                                       # ex. to stop at EOF
    #code 2 , if error occurs
'''
