Save and loading Unity 5?

Question

I am geting these varnings in the unity 5 console: The class named 'LoadandSave' is not derived from MonoBehaviour or ScriptableObject!
 GameObject (named 'GameSpawner') references runtime script in scene file.Fixing! 
But I am not getting any errors or varnings in Visual Studio.

using UnityEngine;

using UnityEngine.UI;

using UnityEngine.SceneManagement;

using System.IO;

using System.Runtime.Serialization.Formatters.Binary;

 public class GameData : MonoBehaviour
 public Text ScoreText;
 public Text Highscoretext;
 public Transform player;
 public static float Highscore = 0;
 void Update()
 {
     ScoreText.text = player.transform.position.x.ToString("0");
     if (player.transform.position.x > Highscore)
     {
         Highscoretext.text = player.transform.position.x.ToString("0");
     }
 }
}

 public class LoadandSave
 {
     private void Awake()
     {
         Save();
     }
     public static void Save()
     {
         BinaryFormatter binaryformatter = new BinaryFormatter();
         using (FileStream fs = new FileStream("gamesave.bin", FileMode.Create, FileAccess.Write))
         {
             binaryformatter.Serialize(fs, GameData.Highscore);
         }
         SceneManager.LoadScene(0);
     }
     public static void Load()
     {
         if (!File.Exists("gamesave.bin"))
         {
             return;
         }
         BinaryFormatter binaryformatter = new BinaryFormatter();
         using (FileStream fs = new FileStream("gamesave.bin", FileMode.Open, FileAccess.Read))
         {
             GameData.Highscore = (int)binaryformatter.Deserialize(fs);
         }
     }
 }
I have tried adding :MonoBehaviour att the end of public class LoadandSave. 
But then the unity 5 editor wont start play. And just craches.

Save and loading Unity 5?

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