def kaibun_parse(str,l)
	str1 = str[0..l-1]
	l.times{|i|
		tmp = str1[i..l-1]
		if tmp == tmp.reverse && tmp != str 
			return tmp
		end
	}
end

def kaibun_max(str,n)
	if n == 0
		return ""
	else
		return [kaibun_max(str,n-1),kaibun_parse(str,n)].max{|a,b|a.size <=> b.size}
	end
end

s = gets
puts kaibun_max(s,s.size).size