Unity 2D collect and counting but counting system is not right,Unity 2D collect obj and count it but there's problem about counting

so I try to make part of the game that has a scene where the player has to collect 5 papers and then it's gonna be a condition to another step. I use code from this video (https://www.youtube.com/watch?v=D0lx90n0s-4&t=626s&ab_channel=JimmyVegas) and when I test it. it counts normally when it's not separate like this

and then when I separate all 5 to all around the map. it's going wrong. some of it doesn't count on the score. and this is the code i use for count paper

PaperScore.cs

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 
 public class PaperScore : MonoBehaviour
 {
    
     public GameObject PaperText;
     public static int thescore;
 
      void Update()
     {
         PaperText.GetComponent<Text>().text = "Paper:" + thescore / 2;
 
     }
 }

CollectPaper.cs

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class CollectPaper : MonoBehaviour
 {
      void OnTriggerEnter2D(Collider2D collision)
     {
         PaperScore.thescore += 1;
         Destroy(gameObject);
 
     }
 }
 

thank you for your help