def parin? s
  !(0..s.size/2).any?{|i|s[i]!=s[s.size-1-i]}
end

a=1
s=gets.chomp
for i in 0...s.size
  for j in (i+1)...s.size
    d=s[i..j]
    a=[a,d.size].max if d.size<s.size&&parin?(d)
  end
end
p a