Here is my code 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class NumberWizard : MonoBehaviour {
int maxNum = 1000;
int minNum = 1;
int guessNum = 500;
// Use this for initialization
void Start ()
{
Debug.Log("I'm a wizard and I can guess any number that you are thinking!");
Debug.Log("Pick a number in your head. Do not tell me. I will guess it anyway.");
Debug.Log("The highest number you can pick is: " + maxNum);
Debug.Log("The lowest number you can pick is: " + minNum);
Debug.Log("Is your number " + guessNum + "? If it is, press ENTER");
Debug.Log("If not, press UP if your number is higher. Press DOWN if it is lower");
maxNum = maxNum + 1;
}
// Update is called once per frame
void Update () {
//Detect when the Up key is pressed down
if (Input.GetKeyDown(KeyCode.UpArrow))
{
Debug.Log("Up Arrow key was pressed.");
minNum = guessNum;
guessNum = (maxNum + minNum) / 2;
Debug.Log("I guess your number is: " + guessNum + ". Press ENTER if this is your number");
}
//Detect when the Down key is pressed down
else if (Input.GetKeyDown(KeyCode.DownArrow))
{
Debug.Log("Down Arrow key was pressed.");
maxNum = guessNum;
guessNum = (maxNum + minNum) / 2;
Debug.Log("I guess your number is: " + guessNum + ". Press ENTER if this is your number");
}
//Detect when the Return key is pressed down
else if (Input.GetKeyDown(KeyCode.Return))
{
Debug.Log("I always knew your number was " + guessNum + ". Next time pick a harder number to guess");
}
}
}