Sum Seconds

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

namespace Sum_Seconds_best
{
    class Program
    {
        static void Main(string[] args)
        {
            var t1 = int.Parse(Console.ReadLine());
            var t2 = int.Parse(Console.ReadLine());
            var t3 = int.Parse(Console.ReadLine());
            var min = 0;

            int sec = t1 + t2 + t3;

            if ((sec > 59) && (sec <= 119))
            {
                min++;
                sec = sec - 60;
            }
            if ((sec >= 120) && (sec <= 179))
            {
            min = 2;
            sec = sec - 120;
            }
            if (sec < 10)
            {
                Console.WriteLine(min + ":" +"0" + sec);
            }
            else
            {
                Console.WriteLine(min + ":" + sec);
            }
        }
    }
}