I am writing a game on Unity, it came to the inventory, I wrote the code and I got an error! What to do?

Question

C++ / C#

Here is the error:
'Camera' does not contain a definition for 'ScrenToWorldPoint', and no accessible extension method 'ScrenToWorldPoint' could be found that takes the type 'Camera' as the first argument (perhaps a using directive or an assembly reference is missing).

Here is the code:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;

public class Inventory : MonoBehaviour
{
    public DataBase data;
    public List<ItemInventory> items = new List<ItemInventory>();

    public GameObject gameObjShow;

    public GameObject InventoryMainObject;
    public int maxCount;

    public Camera cam;
    public EventSystem es;

    public int currentID;
    public ItemInventory currentItem;

    public RectTransform movingObject;
    public Vector3 offset;

    public void Start() 
    {
        if (items.Count == 0)
        {
            AddGraphics();
        }

        for(int i = 0; i < maxCount; i++) //тест заполнить рандомные ячейки
        {
            AddItem(i, data.items[Random.Range(0, data.items.Count)], Random.Range(1, 99));
        }
        UpdateInventory();
    }

    public void Update() 
    {
        if (currentID != -1)
        {
            MoveOject();
        }
    }

    public void AddItem(int id, Item item, int count)
    {
        items[id].id = item.id;
        items[id].count = count;
        items[id].itemGameObj.GetComponent<Image>().sprite = item.img;

        if (count > 1 && item.id != 0)
        {
            items[id].itemGameObj.GetComponentInChildren<Text>().text = count.ToString();
        }
        else
        {
            items[id].itemGameObj.GetComponentInChildren<Text>().text = "";
        }
    }

    public void AddInventoryItem(int id, ItemInventory invItem)
    {
        items[id].id = invItem.id;
        items[id].count = invItem.count;
        items[id].itemGameObj.GetComponent<Image>().sprite = data.items[invItem.id].img;

        if (invItem.count > 1 && invItem.id != 0)
        {
            items[id].itemGameObj.GetComponentInChildren<Text>().text = invItem.count.ToString();
        }
        else
        {
            items[id].itemGameObj.GetComponentInChildren<Text>().text = "";
        }
    }

    public void AddGraphics()
    {
        for (int i = 0; i < maxCount; i++)
        {
            GameObject newItem = Instantiate(gameObjShow, InventoryMainObject.transform) as GameObject;

            newItem.name = i.ToString();

            ItemInventory ii = new ItemInventory();
            ii.itemGameObj = newItem;

            RectTransform rt = newItem.GetComponent<RectTransform>();
            rt.localPosition = new Vector3(0, 0, 0);
            rt.localScale = new Vector3(1, 1, 1);
            newItem.GetComponentInChildren<RectTransform>().localScale = new Vector3(1, 1, 1);

            Button tempButton = newItem.GetComponent<Button>();

            tempButton.onClick.AddListener(delegate { SelectObject(); });

            items.Add(ii);
        }
    }

    public void UpdateInventory()
    {
        for (int i = 0; i < maxCount; i++)
        {
            if (items[i].id != 0 && items[i].count > 1)
            {
                items[i].itemGameObj.GetComponentInChildren<Text>().text = items[i].count.ToString();
            }
            else
            {
                items[i].itemGameObj.GetComponentInChildren<Text>().text = "";
            }

            items[i].itemGameObj.GetComponent<Image>().sprite = data.items[items[i].id].img;
        }
    }

    public void SelectObject()
    {
        if (currentID == -1)
        {
            currentID = int.Parse(es.currentSelectedGameObject.name);
            currentItem = CopyInventoryItem(items[currentID]);
            movingObject.gameObject.SetActive(true);
            movingObject.GetComponent<Image>().sprite = data.items[currentItem.id].img;

            AddItem(currentID, data.items[0], 0);
        }
        else
        {
            AddInventoryItem(currentID, items[int.Parse(es.currentSelectedGameObject.name)]);

            AddInventoryItem(int.Parse(es.currentSelectedGameObject.name), currentItem);
            currentID = -1;

            movingObject.gameObject.SetActive(false);
        }
    }

    public void MoveOject()
    {
        Vector3 pos = Input.mousePosition + offset;
        pos.z = InventoryMainObject.GetComponent<RectTransform>().position.z;
        movingObject.position = cam.ScrenToWorldPoint(pos);
    }

    public ItemInventory CopyInventoryItem(ItemInventory old)
    {
        ItemInventory New = new ItemInventory();

        New.id = old.id;
        New.itemGameObj = old.itemGameObj;
        New.count = old.count;

        return New;
    }

}

  [System.Serializable]

public class ItemInventory
{
    public int id;
    public GameObject itemGameObj;

    public int count;
}

Answer 1

Firstly, thank you very much for the lesson code) Otherwise, instead of 1 of yours, I had 9 other errors.
And all you need to do in your code:
In the word "ScrenToWorldPoint", - add one letter e - to get Screen...
then everything will work.