a = raw_input()
b = map(int, a)
n=[]
while b:
smallest = min(b)
n.append(smallest)
b.remove(smallest)
print
print ''.join(map(str, n))
YSA9IHJhd19pbnB1dCgpCmIgPSBtYXAoaW50LCBhKQpuPVtdCndoaWxlIGI6CiAgICBzbWFsbGVzdCA9IG1pbihiKQogICAgbi5hcHBlbmQoc21hbGxlc3QpCiAgICBiLnJlbW92ZShzbWFsbGVzdCkKcHJpbnQKcHJpbnQgJycuam9pbihtYXAoc3RyLCBuKSk=