Elevator script problem (Java)

Hi all, I am new to Unity! I do lift. When you press E, the elevator should move to the next floor (it works), but when you reach the top floor, the elevator continues engines on. Please help fix it. How to make the elevator did not move further up on reaching an endpoint, even when you press E, and how to achieve smooth motion lift?

Please help me! Thank you!

Here's a script that I wrote (elevator should be located initially in the zero-point coordinates):

 var elevator: Transform;
 var player: Transform;
 private var nextPuch: float = 0.5;
 private var eleRate : float = 5.0;
 private var curPos: Vector3;
 
 function OnTriggerEnter () {
 var GO = elevator;
 var GO1 = player;
     GO1.transform.parent = GO.transform;
 }
  
 function OnTriggerExit () {
 var GO = elevator;
 var GO1 = player;
     GO1.transform.parent = null;
 }
 
 function Update () {
 curPos = transform.position;
 
 var eleHeight = Vector3(0, 5, 0);
 
 //elevator should be located initially in the zero-point coordinates
 var floor01 = Vector3(0, 0, 0);
 var floor02 = Vector3(0, 5, 0);
 var floor03 = Vector3(0, 10, 0);
 var floor04 = Vector3(0, 15, 0);
 var floor05 = Vector3(0, 20, 0);
 
 if (curPos != floor01 && Input.GetKey(KeyCode.E) && Time.time > nextPuch) {
     elevator.transform.position = curPos + eleHeight;
     nextPuch = Time.time + eleRate;
     }
 else if (curPos != floor02 && Input.GetKey(KeyCode.E) && Time.time > nextPuch) {
     elevator.transform.position = curPos + eleHeight;
     nextPuch = Time.time + eleRate;
     }
 else if (curPos != floor03 && Input.GetKey(KeyCode.E) && Time.time > nextPuch) {
     elevator.transform.position = curPos + eleHeight;
     nextPuch = Time.time + eleRate;
     }
 else if (curPos != floor04 && Input.GetKey(KeyCode.E) && Time.time > nextPuch) {
     elevator.transform.position = curPos + eleHeight;
     nextPuch = Time.time + eleRate;
     }
 else if (curPos != floor05 && Input.GetKey(KeyCode.E) && Time.time > nextPuch) {
     elevator.transform.position = curPos;
     nextPuch = Time.time + eleRate;
     }
 return;
 }