s=gets.chop.chars
t=s.sort
f=s.size-1
(0..f).map{|i|
  if s[i]!=t[f]
    x=s.rindex t[f]
    y=s[i]
    s[i]=t[f] 
    s[x]=s[i]
    break
  end
}
$><<s*''