Cant use 'var' to define Vector3?

Getting an error for using var, tried a few things but nothing works or makes it worse. How do I define a Vector variable?

	private var pos = new Vector3(0, 0, 0);
	 
     void Update()
	{

			pos = Camera.main.ScreenToWorldPoint (Vector3 (Input.GetTouch (0).position.x, Input.GetTouch (0).position.y, 5));

			transform.position = new Vector3 (pos.x, pos.y, pos.z);

	}

private Vector3 pos = Vector3.Zero;

      void Update()
     {
             pos = Camera.main.ScreenToWorldPoint (Vector3 (Input.GetTouch (0).position.x, Input.GetTouch (0).position.y, 5));
             transform.position = new Vector3 (pos.x, pos.y, pos.z);
 
     }

Its a lower case z Vector3.zero

You can’t use the var keyword for fields or constants, only local variables

var vect = Vector3.zero; // not ok

public void Update() {
    var vect1 = Vector3.zero; // ok
}