do
local h,s={},io.stdin:read("*l")
for i=0,9 do h[tostring(i)]=0 end
for i=1,#s do h[s:sub(i,i)]=h[s:sub(i,i)]+1 end
for i=9,0,-1 do
	local t=tostring(i)
	if h[t]~=nil then for _=1,h[t] do io.write(t) end end
end print()
end