def find_First_Missing(array,start,end):
     
    if (start > end): 
        return end + 1
    if (start != array[start]): 
        return start; 
    mid = int((start + end) / 2) 
    if (array[mid] == mid): 
        return find_First_Missing(array,mid+1,end) 
    return find_First_Missing(array,start,mid) 
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] 