def max(x, y): 
	if(x > y): 
		return x 
	return y 
def lps(seq, i, j): 
	
	if (i == j): 
		return 1
	if (seq[i] == seq[j] and i + 1 == j): 
		return 2
	if (seq[i] == seq[j]): 
		return lps(seq, i + 1, j - 1) + 2
	return max(lps(seq, i, j - 1), 
			lps(seq, i + 1, j)) 

if __name__ == '__main__': 
	seq = input("Enter the String: ")
	n = len(seq) 
	print("The length of the LPS is", 
				lps(seq, 0, n - 1)) 
	
