Assets\Scripts\GameController.cs(90,20): error CS0117: 'Camera' does not contain a definition for 'main'?

Question

Unity

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

public class GameController : MonoBehaviour
{
    private CubePos nowCube = new CubePos(0, 1, 0);
    public float cubeChangePlaseSpeed = 0.5f;
    public Transform cubeToPlase;
    private float camMoveToYPosition, camMoveSpeed = 2f;

    public GameObject cubeToCreate, allCubes;
    public GameObject[] canvasStartPage;
    private Rigidbody allCubesRB;

    public Color[] bgcolors;
    private Color toCameraColor;

    private bool IsLoose, firstCube;

    private List<Vector3> allCubePosition = new List<Vector3>
    {
        new Vector3(0, 0, 0),
        new Vector3(1, 0, 0),
        new Vector3(-1, 0, 0),
        new Vector3(0, 0, 1),
        new Vector3(0, 0, -1),
        new Vector3(0, 1, 0),
        new Vector3(1, 0, 1),
        new Vector3(-1, 0, -1),
        new Vector3(1, 0, -1),
        new Vector3(-1, 0, 1),
    };

    private int prevCountMaxHorizontal = 0;
    private Coroutine showCubePlase;
    private Transform mainCam;

    private void Start()
    {
        toCameraColor = Camera.main.backgroundColor;
        mainCam = Camera.main.transform;
        camMoveToYPosition = 8f + nowCube.y - 1f;

        allCubesRB = allCubes.GetComponent<Rigidbody>();
        showCubePlase = StartCoroutine(ShowCubePlase());
    }

    private void Update()
    {
        if ((Input.GetMouseButtonDown(0) || Input.touchCount > 0) && cubeToPlase != null && !EventSystem.current.IsPointerOverGameObject())
        {
#if !UNITY_EDITOR
            if (Input.GetTouch(0).phashe != TouchPhase.Began)
                return;


#endif
            if (!firstCube)
            {
                firstCube = true;
                foreach (GameObject obj in canvasStartPage)
                    Destroy(obj);
            }

            GameObject newCube = Instantiate(cubeToCreate, cubeToPlase.position, Quaternion.identity) as GameObject;

            newCube.transform.SetParent(allCubes.transform);
            nowCube.setVector(cubeToPlase.position);
            allCubePosition.Add(nowCube.getVector());

            allCubesRB.isKinematic = true;
            allCubesRB.isKinematic = false;

            SpawnPositions();
            MoveCameraCangeBG();
        }

        if (!IsLoose && allCubesRB.velocity.magnitude > 0.1f)
        {
            Destroy(cubeToPlase.gameObject);
            IsLoose = true;
            StopCoroutine(showCubePlase);
        }

        mainCam.localPosition = Vector3.MoveTowards(mainCam.localPosition, new Vector3(mainCam.localPosition.x, camMoveToYPosition, mainCam.localPosition.z), camMoveSpeed * Time.deltaTime);

        if (Camera.main.backgroundColor != toCameraColor)
            Camera.main.backgroundColor = Color.Lerp(Camera.main.backgroundColor, toCameraColor, Time.deltaTime / 1.5f);
    }

    IEnumerator ShowCubePlase()
    {
        while (true)
        {
            SpawnPositions();
            yield return new WaitForSeconds(cubeChangePlaseSpeed);
        }
    }

    private void SpawnPositions()
    {
        List<Vector3> position = new List<Vector3>();
        if (IsPositionEmpty(new Vector3(nowCube.x + 1, nowCube.y, nowCube.z))
            && nowCube.x + 1 != cubeToPlase.position.x)
            position.Add(new Vector3(nowCube.x + 1, nowCube.y, nowCube.z));
        if (IsPositionEmpty(new Vector3(nowCube.x - 1, nowCube.y, nowCube.z))
            && nowCube.x - 1 != cubeToPlase.position.x)
            position.Add(new Vector3(nowCube.x - 1, nowCube.y, nowCube.z));
        if (IsPositionEmpty(new Vector3(nowCube.x, nowCube.y + 1, nowCube.z))
            && nowCube.y + 1 != cubeToPlase.position.y)
            position.Add(new Vector3(nowCube.x, nowCube.y + 1, nowCube.z));
        if (IsPositionEmpty(new Vector3(nowCube.x, nowCube.y - 1, nowCube.z))
            && nowCube.y - 1 != cubeToPlase.position.y)
            position.Add(new Vector3(nowCube.x, nowCube.y - 1, nowCube.z));
        if (IsPositionEmpty(new Vector3(nowCube.x, nowCube.y, nowCube.z + 1))
            && nowCube.z + 1 != cubeToPlase.position.z)
            position.Add(new Vector3(nowCube.x, nowCube.y, nowCube.z + 1));
        if (IsPositionEmpty(new Vector3(nowCube.x, nowCube.y, nowCube.z - 1))
            && nowCube.z - 1 != cubeToPlase.position.z)
            position.Add(new Vector3(nowCube.x, nowCube.y, nowCube.z - 1));

        if (position.Count > 1)
            cubeToPlase.position = position[UnityEngine.Random.Range(0, position.Count)];
        else if (position.Count == 0)
            IsLoose = true;
        else
            cubeToPlase.position = position[0];
    }

    private bool IsPositionEmpty(Vector3 targetPos)
    {
        if (targetPos.y == 0)
            return false;

        foreach (Vector3 pos in allCubePosition)
        {
            if (pos.x == targetPos.x && pos.y == targetPos.y && pos.z == targetPos.z)
                return false;
        }
        return true;
    }

    private void MoveCameraCangeBG()
    {
        int maxX = 0, maxY = 0, maxZ = 0, maxHor;

        foreach (Vector3 pos in allCubePosition)
        {
            if (Mathf.Abs(Convert.ToInt32(pos.x)) > maxX)
                maxX = Convert.ToInt32(pos.x);
            if (Convert.ToInt32(pos.y) > maxY)
                maxY = Convert.ToInt32(pos.x);
            if (Mathf.Abs(Convert.ToInt32(pos.z)) > maxZ)
                maxZ = Convert.ToInt32(pos.z);
        }

        camMoveToYPosition = 8f + nowCube.y - 1f;

        maxHor = maxX > maxZ ? maxX : maxZ;
        if (maxHor % 3 == 0)
        {
            mainCam.localPosition += new Vector3(0, 0, 2.5f);
            prevCountMaxHorizontal = maxHor;
        }

        if (maxY >= 10)
            toCameraColor = bgcolors[3];
        else if (maxY >= 7)
            toCameraColor = bgcolors[2];
        else if (maxY >= 5)
            toCameraColor = bgcolors[1];
        else if (maxY >= 2)
            toCameraColor = bgcolors[0];
    }
}

struct CubePos
{
    public int x, y, z;

    public CubePos(int x, int y, int z)
    {
        this.x = x;
        this.y = y;
        this.z = z;
    }

    public Vector3 getVector()
    {
        return new Vector3(x, y, z);
    }

    public void setVector(Vector3 pos)
    {
        x = Convert.ToInt32(pos.x);
        y = Convert.ToInt32(pos.y);
        z = Convert.ToInt32(pos.z);
    }
}