The compiler throws error CS1520 error: the method must have a return type please help

  1  using System.Collections;
  2  using System.Collections.Generic;
  3  using UnityEngine;
  4  using UnityEngine.UI;
  5  using TMPro;
  6  using UnityEngine.Events;
  7  using UnityEngine.EventSystems;
  8  using UnityEngine.SceneManagement;
  9  
 10  public class Ahivments : MonoBehaviour
 11  {
 12      public int total_Coin_Vanya;
 13      public int Coin_Vanya;
 14      [SerializeField] bool isFirst;
 15      
 16  
 17      public string[] arrayTitles;
 18      public Sprite[] arraySprites;
 19      public GameObject button;
 20      public GameObject content;
 21  
 22      private List<GameObject> list = new List<GameObject>();
 23      private VerticalLayoutGroup _group;
 24  
 25  
 26      // Start is called before the first frame update
 27      void Start()
 28      {
 29      Coin_Vanya = PlayerPrefs.GetInt("Coin_Vanya");
 30      total_Coin_Vanya = PlayerPrefs.GetInt("total_Coin_Vanya");
 31      PlayerPrefs.SetInt("isFirst", isFirst ? 1 : 0);
 32  
 33      RectTransform recT = content.GetComponent<RectTransform>();
 34      recT.transform.localPosition = new Vector3(0.0f, 0.0f, 0.0f);
 35      _group = GetComponent<VerticalLayoutGroup>();
 36      setAchievs();
 37  
 38      if(isFirst)
 39      {
 40         StartCoroutine(IdleFarm());
 41      }
 42     
 43      }
 44  
 45      private void RemovedList()
 46      {
 47       foreach (var elem in list)
 48       {
 49        Destroy(elem);
 50       }
 51       list.Clear();
 52      }
 53  
 54      void setAchievs()
 55      {
 56       RectTransform recT = content.GetComponent<RectTransform>();
 57       recT.transform.localPosition = new Vector3(0.0f, 0.0f, 0.0f);
 58       RemovedList();
 59       if (arrayTitles.Length > 0)
 60      {
 61        var pr1 = Instantiate(button, transform);
 62        var h = pr1.GetComponent<RectTransform>().rect.height;
 63        var tr = GetComponent<RectTransform>();
 64        tr.sizeDelta = new Vector2(tr.rect.width, h * arrayTitles.Length);
 65        Destroy(pr1);
 66        for (var i = 0; i < arrayTitles.Length; i++)
 67        {
 68         var pr = Instantiate(button, transform);
 69         pr.GetComponentInChildren<Text>().text = arrayTitles[i];
 70         pr.GetComponentsInChildren<Image>()[1].sprite = arraySprites[i];
 71         var i1 = i;
 72         pr.GetComponent<Button>().onClick.AddListener(() => GetAchievement(i1));
 73         list.Add(pr);
 74        }
 75      }
 76      }
 77  
 78      void GetAchievement(int id)
 79      {
 80        switch(id)
 81        {
 82  
 83         case 0:
 84         Debug.Log(id);
 85         break;
 86  
 87         case 1:
 88         Debug.Log(id);
 89         Coin_Vanya += 10;
 90         PlayerPrefs.SetInt("Coin_Vanya", Coin_Vanya);
 91         break;
 92        }
 93      }
 94  
 95     
 96  
 97      IEnumerator IdleFarm()
 98      {
 99       yield return new WaitForSeconds(1);
100       Coin_Vanya++;
101       Debug.Log(Coin_Vanya);
102       PlayerPrefs.SetInt("Coin_Vanya", Coin_Vanya);
103       StartCoroutine(IdleFarm());
104      }
105  
106      public void ToMeinMenu()
107      {
108      SceneManager.LoadScene(0);
109      }
110  }