def uniquePaths(m, n): dp = [[1]*n for _ in range(m)] for i in range(1, m): for j in range(1, n): dp[i][j] = (dp[i - 1][j] + dp[i][j - 1]) % (10**9 + 7) return dp[m - 1][n - 1] if __name__ == "__main__": m, n = map(int, input().split()) print(uniquePaths(m, n))