s = gets.strip

len_max = 0
(1...s.length).each do |i|
	len = 1
	(1...s.length).each do |j|
		break if i - j < 0 || i + j >= s.length
		if s[i - j] == s[i + j]
			len += 2
		else
			break
		end
	end
	len_max = [len_max, len].max
end
# p len_max

(1...s.length).each do |i|
	len = 0
	(1...s.length).each do |j|
		break if i - j + 1 < 0 || i + j >= s.length
		if s[i - j + 1] == s[i + j]
			len += 2
		else
			break
		end
	end
	len_max = [len_max, len].max
end
p len_max