Destroy Out Of Bounds

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class DestroyOutOfBounds : MonoBehaviour
{
    //script to destroy gameobject afte they leave the scene
    private float topBound = 30.0f;
    private float lowerBound = -50.0f;
    private float sideBound = 30f;
    private GameManager gameManager;

    void Start()
    {
        //refernecing the game manager
        gameManager = GameObject.Find("GameManager").GetComponent<GameManager>();
    }
    //when food or animal reach a certain top or bottom positon they are destroyed
    //takes away a life when animal reaches boundary
    void Update()
    {
        if (transform.position.z > topBound)
        {
            Destroy(gameObject);
        }
        else if (transform.position.z < lowerBound)
        {
            gameManager.AddLives(-1);
            Destroy(gameObject);
        }
        else if (transform.position.x > sideBound)
        {
            gameManager.AddLives(-1);
            Destroy(gameObject);
        }
        else if (transform.position.x < -sideBound)
        {
            gameManager.AddLives(-1);
            Destroy(gameObject);

        }
    }
}