def binomial_coeff(n, k): 
	C = [[0 for j in range(k + 1)] 
			for i in range(n + 1)] 
	for i in range(0, n + 1): 
		for j in range(0, min(i, k) + 1): 
			if (j == 0 or j == i): 
				C[i][j] = 1
			else: 
				C[i][j] = (C[i - 1][j - 1] 
							+ C[i - 1][j]) 
	return C[n][k] 
def lobb_num(n, m): 
	return (((2 * m + 1) *
		binomial_coeff(2 * n, m + n)) 
					/ (m + n + 1))