Multi Touch Disable on Virtual Joy-pad (FPS)

I wrote a script to rotate around the player in FPS as below...The problem is that when i use multiple fingers it does inappropriate behavior...

I have attached this script to the image on my canvas.....i want to disable multi touch on that image....how can i do that....Thanks in advance

 using UnityEngine;
 using System.Collections;
 using UnityEngine.UI;
 using UnityEngine.EventSystems;
 
 public class VirtualPad : MonoBehaviour,IDragHandler,IPointerDownHandler {
 
 
     
     public Vector2 origin;
     public Vector2 CurrentPosition;
     public Vector2 DirectionRaw;
     public GameObject player;
     public GameObject player_cam;
     public float sensetivity;
     
 
 
     public virtual void OnDrag(PointerEventData data)
     {
         CurrentPosition = data.position;
         DirectionRaw = CurrentPosition - origin;
 
 
     
         player.transform.Rotate(Vector3.up*Time.deltaTime* DirectionRaw.x*sensetivity,Space.World);
 
         player_cam.transform.Rotate (Time.deltaTime*-DirectionRaw.y*sensetivity, 0, 0);
 
         origin.x = CurrentPosition.x;
         origin.y = CurrentPosition.y;

 
         
     }
     
  virtual void OnPointerDown(PointerEventData data)
     {
         origin.x = data.position.x;
         origin.y = data.position.y;
         OnDrag (data);
 
     }
 
 
 }