A = gets.chomp
N = A.size

0.upto(N) do |i|
  str = A.dup

  i.times do |i|
    str << '?'
  end

  l = 0
  r = str.size - 1
  ok = true

  while l < r && ok
    if str[l] != str[r]
      if str[r] == '?'
        str[r] = str[l]
      else
        ok = false
      end
    end

    l += 1
    r -= 1
  end

  if ok
    puts str
    break
  end
end