def max_sum_subseq(A):
    
    n = len(A)
    if n == 1:
        return A[0]
    look_up = [None] * n
    look_up[0] = A[0]
    look_up[1] = max(A[0], A[1])
    for i in range(2, n):
        look_up[i] = max(look_up[i - 1], look_up[i - 2] + A[i])
        look_up[i] = max(look_up[i], A[i])
    return look_up[n - 1]
def count_ways(n):
	 
	A = [0] * (n + 1) 
	B = [0] * (n + 1) 
	A[0] = 1
	A[1] = 0
	B[0] = 0
	B[1] = 1
	for i in range(2, n+1): 
		A[i] = A[i - 2] + 2 * B[i - 1] 
		B[i] = A[i - 1] + B[i - 2] 
	return A[n] 