s = gets
n = s.size
kaibun_max = 0
tmp = ""
n.times{|i|
	i.upto(n-1){|j|
		tmp = s[i..j]
		if tmp == tmp.reverse && tmp.size < s.size
			kaibun_max = [kaibun_max,tmp.size].max
		end
	}
}

puts kaibun_max