def find_length(string, n):
	 
	current_sum = 0
	max_sum = 0
	for i in range(n): 
		current_sum += (1 if string[i] == '0' else -1) 
		if current_sum < 0: 
			current_sum = 0
		max_sum = max(current_sum, max_sum) 
	return max_sum if max_sum else 0
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] 