def sum_even_and_even_index(arr,n):
      
    i = 0
    sum = 0
    for i in range(0,n,2): 
        if (arr[i] % 2 == 0) : 
            sum += arr[i]  
    return sum
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] 