# your code goes here

n=STDIN.gets
n=n.split("")
cs=[0,0,0,0,0,0,0,0,0,0]

for n1 in n
	cs[n1.to_i]+=1
end
for i in 0..9
	j=9-i
	cs[j].times do |k|
		print j
	end
end
puts ""