More complex Fill Handle use

Hi, I need to write down a whole bunch of titles that are almost all alike. However, I can't use the Fill Handle directly because the titles look like this :

Green Monster G1 P1
Green Monster G1 P2
Green Monster G1 P3
Green Monster G2 P1
Green Monster G2 P2
...
and so on

I have a small base in programming, but I never programmed anything in excel before.

Could someone help me find out if there is a way I can do this efficiently, I have over 5000 entries to put in!

Thank you very much!

Maybe like this.

Do you have questions, just ask.