Find the Terrain Width and Height

Hi, fellow unity developers :)

I wrote a script for a RTS camera that prevents the camera from going off the terrain (when the player moves the camera with WASD / arrow keys, found in another script, not included below).

As you can see, in my code below, I have hardcoded the width and height of the terrain. I want to be able to automatically detect the width and height of the terrain.

Note: I am very new to Unity and C# so if you know the answer, please provide a complete code not just fragments, ty :)

 using System.Collections;
 using UnityEngine;
 
 public class CameraBounder : MonoBehaviour {
 
     int minXBound = 50;
     int maxXBound = 50;
     int minZBound = 100;
     int maxZBound = 200;
     int terrainWidth = 500;
     int terrainHeight = 500;
 
     // Use this for initialization
     void Start () {
     }
     
     // Update is called once per frame
     void Update () {
         Debug.Log("X: " + transform.position.x + " Z: " + transform.position.z);
 
         if (transform.position.x > terrainWidth - maxXBound) {
             transform.position = new Vector3 ((terrainWidth-maxXBound), transform.position.y, transform.position.z);
         } 
         if (transform.position.x < minXBound) {
             transform.position = new Vector3 (minXBound, transform.position.y, transform.position.z);
         }
         if (transform.position.z > terrainHeight - maxZBound) {
             transform.position = new Vector3 (transform.position.x, transform.position.y, (terrainHeight-maxZBound));
         }
         if (transform.position.z < minZBound) {
             transform.position = new Vector3 (transform.position.x, transform.position.y, minZBound);
         }
     }
 
 }