Time + 15 Minutes

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

namespace Time_15_Minutes
{
    class Program
    {
        static void Main(string[] args)
        {
            var hours = int.Parse(Console.ReadLine());
            var mins = int.Parse(Console.ReadLine()) + 15;

            if (mins > 59)
            {
                hours += 1;
                mins = mins - 60;
                Console.WriteLine("{0}:{1:00}", hours, mins);
            }
            else if (hours > 23)
            {
                hours = hours - 24;
                Console.WriteLine("{0}:{1:00}", hours, mins);
            }
            else
            {
                Console.WriteLine("{0}:{1:00}", hours, mins);
            }
        }
    }
}