I guess this is why we have regex lmao

LOL mine was so much more complicated than this....

Looks much better 👍

Yes but it is the matter of tense. He even properly uses 'takes' but not 'drops'.
"Bob is going to the store and drop an apple." is not correct.

Its very obvious if you read it...

1. "There is a bus moving in the city, and it takes and drop some people in each bus stop."
   => "There is a bus moving in the city which takes and drops off some people at each bus stop."
2. "Elements of each pair represent number of people get into bus (The first item) and number of people get off the bus (The second item) in a bus stop."
   => "Elements of each pair represent the number of people that get on the bus (the first item) and the number of people that get off the bus (the second item) at a bus stop."
3. "Your task is to return number of people who are still in the bus..."
   => "Your task is to return the number of people who are still on the bus..."

The writer uses 'in the bus' instead of 'on', they don't use the word 'the' when necessary, and even doesn't use the right tense of 'drop'.

Hm I tried to put this with null instead of 0, anyone know why this works over null?

Make sure to thoroughly read the details and remember what RGB can and cannot be.