void Update () {
  speed = 5f;
  //if (Input.touchCount == 1){
  if (Input.GetMouseButtonDown (0)) {
   target = Camera.main.ScreenToWorldPoint (Input.mousePosition);
   target.z = transform.position.z;        
   //  target.y = transform.position.y;      

   if (move == false)
    move = true;

  }
  if (move == true)
   transform.position = Vector3.MoveTowards (transform.position, target, speed * Time.deltaTime);
    }
}