C# Check for multiple key presses and their combinations

Hello,

Is there any way to chceck if was pressed key 1 and 2, than save that it happened?

I have:

 if (Input.GetKey("1"))
                 if (Input.GetKey("2"))
                         jd.enabled = true;

 if (Input.GetKey("1"))
             if (Input.GetKey("3"))
                 jt.enabled = true;

jd.enabled = true --> that is for displaying object

First issue I have with this is that I have to hold down simultaneously key 1 and 2, I want to press 1 and then 2 in let's say 2 second spam. And it should work if you press 2 and then 1.

The other issue is that I can't figure out how to check if combination 1,2 and 1,3 was pressed and base on that for example write some text. But only if both were pressed.

Something like this is not valid possibility:

     if (Input.GetKey("1"))
                     if (Input.GetKey("2"))
                              if (Input.GetKey("1"))
                                        if (Input.GetKey("3"))
                                                 Debug.Log("Something")

I have 15 possible combination of key presses and around 2000 possible output combinations.

I'm totally new and have no idea how to do this... thank you for any help!