how can i access list of sprites in my code ??

i have 42 sprites, and i want them to access in my code. to select random 21 of them. how can i add them in a list or array? i want to color them red and to other sprites green . this is not working folder is named MAPS and sprites are tagged as country any idea to access them ??

 Sprite[] countries = Resources.LoadAll<Sprite>("MAPS");
     sr = GetComponent<SpriteRenderer>();
     names = new string[countries.Length];

     for (int i = 0; i < names.Length; i++)
     {
         names[i] = countries[i].name;
         //0 = red
         //1 = green
         if (UnityEngine.Random.Range(0, 2) == 0)
         {
             this.GetComponent<SpriteRenderer>().color = Color.red;
         }
         else
         {
             this.GetComponent<SpriteRenderer>().color = Color.green;
         }
     }