Timer Clock

using UnityEngine;
using System.Collections;
using UnityEngine.UI;

public class Timer : MonoBehaviour {

public float startTime;
public float staTime;
public static double timeRemaining;
public Text MissionTimeText;
public GameObject Gameover;
public GameObject Playing;


void Start()
{
Time.timeScale = 1;
staTime = startTime;
}

void LateUpdate()
{
Countdown();
staTime -= Time.deltaTime;
}

void Countdown(){

timeRemaining = staTime;
ShowTime();

if (timeRemaining < 0 || BoxCount.temp18 == 0) {
timeRemaining = 0;
Gameover.SetActive (true);
Playing.SetActive (false);
Start();
Time.timeScale = 0;

}
}

void ShowTime(){
int hour;
int minutes;
int seconds;
string timeString;
hour = (int)timeRemaining / 3600;
minutes = (int)timeRemaining/60;

seconds = (int)timeRemaining%60;
timeString = hour.ToString() + ":" + minutes.ToString() + ":" + seconds.ToString();
MissionTimeText.text = "Time : " + timeString;
}



}