Touch and drag in the middle of the screen to rotate camera around the player

I’m currently rotating the camera around the player using only this piece of code.

void Update(){
          if (Input.GetMouseButton(0)){
              transform.LookAt(target);
              transform.RotateAround(target.position, Vector3.up, Input.GetAxis("Mouse X") * speed);
              offset = transform.position - target.position;      
          }
    }

By clicking and holding on the left mouse button, i can rotate the camera around the player. How can i do the same but using Touch instead of Mouse, and only do this when clicking on the center of the screen. Thanks in advance.

So apparently the getMouseButton(0) can work as touch input on mobile, so i reused what i already had and did like this: please tell me if there’s a better way to do it.

 void Update(){
          if (Input.GetMouseButton(0)){
            int middleX = Screen.width / 2;
            int middleY = Screen.height / 2;
            Vector3 leftBottom = new Vector3(middleX - windowSize, middleY - windowSize);
            Vector3 rightBottom = new Vector3(middleX + windowSize, middleY - windowSize);
            Vector3 leftTop = new Vector3(middleX - windowSize, middleY + windowSize);
            Vector3 rightTop = new Vector3(middleX + windowSize, middleY + windowSize);

            if (Input.mousePosition.x > leftBottom.x && Input.mousePosition.x < rightBottom.x) {
                if (Input.mousePosition.y > leftBottom.y && Input.mousePosition.y < rightTop.y) {
                    transform.LookAt(target);
                    transform.RotateAround(target.position, Vector3.up, Input.GetAxis("Mouse X") * speed);
                    offset = transform.position - target.position;
                }
            }    
          }
    }