[help]A namespace does not directly contain members such as fields or methods c#

using UnityEngine;
using System.Collections;

public class NumberWizard : MonoBehaviour {

	// Use this for initialization
        int max ;
	    int min ;
	    int guess ;
	
	void Start () {
	StartGame ();
	NextGuess ();
	}
	
	
	void StartGame () {
        
     
    	    max = 1000;
		    min = 1;
		    guess = 500;
		print("======================");
		print("welcome to Number Wizard");
		print("pick a number in your head ,but don't tell me");
		
		print("The highest number you can pick is "    +max);
		print("The lowest number you can pick is "     +min);
		print("Is the number higher or lower than "  +guess);
		print("Up arrow for higher,down for lower,return for equal");}
		
		void NextGuess (){
		guess = ( max + min ) / 2;
		print ("Higher or lower than" + guess); 
		print("Up arrow for higher,down for lower,return for equal");
		max = max + 1;}
		
		}
		
	
	
	// Update is called once per frame     
	    void Update () {
        if(Input.GetKeyDown(KeyCode.UpArrow)){
		  // print("Up arrow pressed");
		   min = guess;
		   NextGuess ();
		   }else if(Input.GetKeyDown(KeyCode.DownArrow)){
		// print("Down Arrow pressed");
			max = guess;
			NextGuess ();
	       } else if(Input.GetKeyDown(KeyCode.Return)){
	       print("I won");
	       StartGame ();}
	      }