I think,it should be strong —— strong enough to hack every code with big mistakes.

I think,it should be weak —— weak enough to not hack those codes with hard-to-hack algorithms(like hash) and little mistakes —— those should be hacked by other user.

I think,at least 97% user who go though pretest should go though system test.

I think,the more effort taken in pretest,the better competition it'll be.