def first_Missing_Positive(arr,n):
     
    ptr = 0
    for i in range(n):
        if arr[i] == 1:
            ptr = 1
            break
    if ptr == 0:
        return(1)
    for i in range(n):
        if arr[i] <= 0 or arr[i] > n:
            arr[i] = 1
    for i in range(n):
        arr[(arr[i] - 1) % n] += n
    for i in range(n):
        if arr[i] <= n:
            return(i + 1)
    return(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] 