def max_sub_array_sum(a, size):
  
  max_so_far = 0
  max_ending_here = 0
  for i in range(0, size):
    max_ending_here = max_ending_here + a[i]
    if max_ending_here < 0:
      max_ending_here = 0
    elif (max_so_far < max_ending_here):
      max_so_far = max_ending_here
  return max_so_far
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] 