Question about inputs

In my 2D game, I want to make it so that if you press A or D twice, you dash instead of running. So far, I don't know how I can program my game to read 2 key inputs in a certain timeframe. Some guidance would be welcome.

 

Code (CSharp):

1. if (Input.GetButtonDown("D")){
2.  
3.             if (Time.time - lastTapTimeRight < tapSpeed) {
4.  
5.                 //Dash
6.  
7.             }
8.  
9.             lastTapTimeRight = Time.time;
10.  
11.         }

 

Thanks, I'll try it soon.

 

tapSpeed and lastTapTimeRight are not used in context.
I'm assuming tapSpeed is a public float I can change to create a window for the input.
for lastTapTimeRight I'm just confused. Maybe it's a float, but I'm not sure how to calculate it, since it's the time since the last input was made.
help...

Edit: Nevermind, turns out I'm really stupid