# your code goes here

n=STDIN.gets
cs=[0,0,0,0,0,0,0,0,0,0]

n.size.times do |i|
	cs[n[i].to_i]+=1
end
for i in 0..9
	j=9-i
	cs[j].times do |k|
		print j.to_s
	end
end
puts ""