s=gets.chomp

if s==s.reverse then
  if s.length == 2 then
    puts 1
    return
  end
  puts s.length-2
  return
end

pos = Array.new()
for i in (0..s.length-1)
        for j in (i+1..s.length-1)
                if s[i..j] == s[i..j].reverse then
                        pos.push(j-i+1)
                end
        end
end

if pos.length == 0 then
  puts 1
elsif
  puts pos.max
end