Problem Statement:

Ahmad is a mathematics scientist, he has many researches and papers on counting theory, he is working now on a new project and he needs your help to calculate the number of paths in a rectangular grid to move from the upper-left corner to bottom-right corner. He can move only down and right.

Input Format:

The input consist of many cases, each case contains two numbers 0<n, m<=100 the number of rows and columns in the grid respectively, input ends when n=m=-1

Output Format:

For each case print one line the number of paths MOD 1000000007

Sample Input:

1 2
2 2
-1 -1

Sample Output:

3
6

Notes:

Explanation of the second case: