def longest_subseq_with_diff_one(arr, n):
	 
	dp = [1 for i in range(n)] 
	for i in range(n): 
		for j in range(i): 
			if ((arr[i] == arr[j]+1) or (arr[i] == arr[j]-1)): 
				dp[i] = max(dp[i], dp[j]+1) 
	result = 1
	for i in range(n): 
		if (result < dp[i]): 
			result = dp[i] 
	return result
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] 