def count_pairs(arr, n, k):
  
  count=0;
  for i in range(0,n):
    for j in range(i+1, n):
      if arr[i] - arr[j] == k or arr[j] - arr[i] == k:
        count += 1
  return count
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] 