Can't use camera.main [SOLVED]

I've been trying to make my character rotate facing the mouse, but when i try to access Camera.main it says that 'Camera does not contain a definition for main'.

Parts of the code is from a previous project me and some friends worked at.

How do i make my camera to the main camera?

Code:

 using UnityEngine;
 using System.Collections;
 
 [RequireComponent(typeof(CharacterController))]
 public class PlayerController : MonoBehaviour
 {
     // Handling
     public float rotationSpeed = 1080;
     public float walkSpeed = 5;
     public float runSpeed = 20;
     public float dashSpeed = 25;
     
     // System
     private Quaternion targetRotation;
     
     // Components
     //public Weapon weapon;
     private CharacterController controller;
     private Camera cam;
     
     // Use this for initialization
     void Start()
     {
         controller = GetComponent<CharacterController>();
         cam = Camera.main;
     }
     
     // Update is called once per frame
     void Update()
     {
         Control();
         
         /*   if (Input.GetButtonDown("ShootL"))
         {
             weapon.ShootLaser();
         }
         
         if (Input.GetButton("ShootR"))
         {
             weapon.ShootRocket();
         }
         
         //Using key G as in the word Grenade
         if (Input.GetButtonDown("Grenade"))
         {  
             weapon.ThrowGrenade();
         }
         
         if (Input.GetButton("Quit"))
         {
             Application.Quit();
         }*/
     }
     
     
     
     void Control()
     {
         Vector3 mousePos = Input.mousePosition;
         mousePos = (new Vector3(mousePos.x, mousePos.y, cam.transform.position.y - transform.position.y));
         targetRotation = Quaternion.LookRotation(mousePos - new Vector3(transform.position.x, 0, transform.position.z));
         transform.eulerAngles = Vector3.up * Mathf.MoveTowardsAngle(transform.eulerAngles.y, targetRotation.eulerAngles.y, rotationSpeed * Time.deltaTime);
         
         Vector3 input = new Vector3(Input.GetAxisRaw("Horizontal"), 0, Input.GetAxisRaw("Vertical"));
         
         Vector3 motion = input;
         motion *= (Mathf.Abs(input.x) == 1 & Mathf.Abs(input.z) == 1) ? .7f : 1;
         
         if ((Input.GetButton("Walk")))
         {
             motion *= walkSpeed;
         } else if ((Input.GetButton("Dash")))
         {
             motion *= dashSpeed;
         } else
         {
             motion *= runSpeed;
         }
         
         motion += Vector3.up * -8;
         
         controller.Move(motion * Time.deltaTime);
     }
 }