There are $$10$$ lights in the classroom and they are labeled $$1$$ to $$10$$, but none of them are on now. Ms. Lily came to the classroom and started pressing the switches from the one which labeled as $1$, pressing one every other one alternatively in order. Then Sam pressed each of the switches marked with an even number of lights $$7$$ times. How many lights that are on now? 
Overseas Competition->Knowledge Point->Number Theory Modules->Odd and Even Numbers