Joann has a robot toy that can walk. The robot can only walk in straight line, and each step can only walk forward for $$1$$ cm or $$3$$ cm. If the robot walks $$4$$ steps forward, it can travel~\uline{~~~~~~~~~~}~different distances. 
Overseas Competition->Knowledge Point->Counting Modules
$1+1+1+1=4$  $3+3+3+3=12$  $1+1+1+3=6$  $1+1+3+3=8$  $1+3+3+3=10$ 