def perfect_squares(a, b):
    
    lists=[]
    for i in range (a,b+1):
        j = 1;
        while j*j <= i:
            if j*j == i:
                 lists.append(i)  
            j = j+1
        i = i+1
    return lists
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] 