Why when i color 4 walls of a grid 10x10 it's coloring 10,9,9,8 and not 10,10,10,10 ?

I'm sure the problem is somewhere with the IF/ELSE conditions and maybe i should use magnitude and math.epsilon but not sure how and how to figure it logic why it's not coloring all the 4 walls.

In the end i'm getting 36 colored blocks instead 40.

This is a screenshot showing on the scene view the grid and the 4 walls of what i mean colored in red,blue,green,yellow

I know that if i color them all they will meet at the 4 corners at 0,0 and 0,9 and 9,0 and 9,9 But still i want to color them all and get 40 colored blocks and not 36.

Now the way i'm coloring it i'm getting this: Red = 10 colored blocks Blue and Green both = 9 colored blocks and Yellow = 8 colored blocks. I wonder how can i use magnitude and math.epsilon if needed and how and what to change in the IF/ELSE statements ?

And this is the script:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class GridGenerator : MonoBehaviour
 {
     public GameObject gridBlock;
     public int gridWidth = 10;
     public int gridHeight = 10;
     public List<Vector3> positions = new List<Vector3>();
     public List<GameObject> blocks = new List<GameObject>();
 
     private GameObject[] wallsParents = new GameObject[4];
 
     void Start()
     {
         wallsParents[0] = GameObject.Find("Top Wall");
         wallsParents[1] = GameObject.Find("Left Wall");
         wallsParents[2] = GameObject.Find("Right Wall");
         wallsParents[3] = GameObject.Find("Bottom Wall");
 
         GenerateGrid();
     }
 
     private void GenerateGrid()
     {
         for (int x = 0; x < gridWidth; x++)
         {
             for (int z = 0; z < gridHeight; z++)
             {
                 GameObject block = Instantiate(gridBlock, Vector3.zero, gridBlock.transform.rotation) as GameObject;
                 block.transform.parent = transform;
                 block.transform.tag = "Block";
                 block.transform.localPosition = new Vector3(x, 0, z);
                 
                 if (block.transform.localPosition.x == 0)//TOP
                 {
                     positions.Add(block.transform.localPosition);
                     block.transform.parent = wallsParents[0].transform;
                     block.transform.name = "TopWall";
                     block.GetComponent<Renderer>().material.color = Color.red;
                 }
                 else if (block.transform.localPosition.z == 0)//LEFT
                 {
                     positions.Add(block.transform.localPosition);
                     block.transform.parent = wallsParents[1].transform;
                     block.transform.name = "LeftWall";
                     block.GetComponent<Renderer>().material.color = Color.blue;
                 }
                 else if (block.transform.localPosition.z == gridWidth - 1)//RIGHT
                 {
                     positions.Add(block.transform.localPosition);
                     block.transform.parent = wallsParents[2].transform;
                     block.transform.name = "RightWall";
                     block.GetComponent<Renderer>().material.color = Color.green;
                 }
 
                 else if (block.transform.localPosition.x == gridHeight - 1)//BOTTOM
                 {
                     positions.Add(block.transform.localPosition);
                     block.transform.parent = wallsParents[3].transform;
                     block.transform.name = "BottomWall";
                     block.GetComponent<Renderer>().material.color = Color.yellow;
                 }
 
                 blocks.Add(block);
             }
         }
     }
 }