def func(n,m): dp = [[1]*(m+1) for i in range(n+1)] for i in range(1,n+1): for j in range(1,m+1): dp[i][j] = dp[i][j-1] + dp[i-1][j]#覆盖 return dp[-1][-1] while True: try: n,m = map(int,input().split()) print(func(n,m)) except: break