OnTimeForExam

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace OnTimeForExam
{
    class OnTimeForExam
    {
        static void Main(string[] args)
        {
            var startExamHour = int.Parse(Console.ReadLine());
            var startExamMinutes = int.Parse(Console.ReadLine());

            var arrivalExamHour = int.Parse(Console.ReadLine());
            var arrivalExamMinutes = int.Parse(Console.ReadLine());

            var examStartInMinutes = startExamHour * 60 + startExamMinutes;
            var studentArrivalInMinutes = arrivalExamHour * 60 + arrivalExamMinutes;

            var diff = Math.Abs(examStartInMinutes - studentArrivalInMinutes);

            var beforeStart = examStartInMinutes > studentArrivalInMinutes;

            if(beforeStart && diff < 60 && diff > 30)
            {
                Console.WriteLine("Early");
                Console.WriteLine("{0} minutes before the start" , diff);
            }
            else if(beforeStart && diff >= 60)
            {
                Console.WriteLine("Early");
                Console.WriteLine("{0}:{1:0#} hours before the start" , diff / 60 , diff % 60);
            }
            else if(!beforeStart && diff >= 60) // => beforeStart = examStartInMinutes < studentArrivalInMinutes
            {
                Console.WriteLine("Late");
                Console.WriteLine("{0}:{1:0#} hours after the start" , diff / 60 , diff % 60);
            }
            else if(!beforeStart && diff != 0)
            {
                Console.WriteLine("Late");
                Console.WriteLine("{0} minutes after the start" , diff);
            }
            else
            {
                Console.WriteLine("On time");
                if(diff != 0)
                {
                    Console.WriteLine("{0} minutes before the start" , diff);
                }
            }
        }
    }
}