  Recently there were many quantum protocols devoted to solve the millionaire
problem and private comparison problem by adding a semi-honest third party.
They all require complicated quantum methods, while still leak a non-trivial
amount of information to at least one of the parties. But it will be shown here
that once the third party is introduced, there are very simple protocols which
require quantum key distribution as the only quantum resource, and the amount
of information leaked can be made arbitrarily small. Furthermore, even a
dishonest third party cannot spoil the protocols. Thus our solutions surpass
all existing protocols on both feasibility and security.
