04. Back In 30 Minutes

using System;

namespace BackIn30Minutes
{
    class Program
    {
        static void Main(string[] args)
        {
            int hour = int.Parse(Console.ReadLine());
            int minute = int.Parse(Console.ReadLine());
            int total = hour * 60 + minute + 30;
            int hourTotal = total / 60;
            int minuteTotal = total % 60;
            if (hourTotal > 23)
            {
                hourTotal %= 24;
            }
            if (minuteTotal > 9)
            {
                Console.WriteLine($"{hourTotal}:{minuteTotal}");
            }
            else
            {
                Console.WriteLine($"{hourTotal}:0{minuteTotal}");
            }
        }
    }
}


With ternary operator and ...:D2 means a decimal with two digits( 7 - 07):


using System;

namespace BackIn30Minutes
{
    class Program
    {
        static void Main(string[] args)
        {
            int total = int.Parse(Console.ReadLine()) * 60 + int.Parse(Console.ReadLine()) + 30;

            Console.WriteLine($"{(total / 60 > 23? default : total / 60)}:{total % 60:D2}");
        }
    }
}