X = gets.chomp
if X[/^.0*$|^(.)\1*$/]
  p -1
else
  Y = X.chars.sort*""
  (Y.size-1).times{|i|
    if Y[i] != Y[i+1]
      Y[i], Y[i+1] = Y[i+1], Y[i]
      break
    end
  }
  puts Y.reverse
end