Tap insteap of MouseUp

Hey, guys I need help turning this script into one that works with android. I want to use a single tap instead of OnMouseUp. Can someone help me?

Code (csharp):

1.  
2. function OnMouseDown() {
3.  
4. audio.clip = sound;
5.         audio.loop = false;
6.  
7.       audio.Play();
8.  
9.  
10.  
11.     if (Vector3.Distance(transform.position,emptyslot.position)==1)
12.     {
13.     xtemp = transform.position.x;
14.     ytemp = transform.position.y;
15.     transform.position.x=emptyslot.position.x;
16.     transform.position.y=emptyslot.position.y;
17.     emptyslot.position.x=xtemp;
18.     emptyslot.position.y=ytemp;
19.    
20.  
21.  
22.