01. Sum Seconds

using System;

namespace demo
{
    class Program
    {
        static void Main(string[] args)
        {
            int time1 = int.Parse(Console.ReadLine()); //50
            int time2 = int.Parse(Console.ReadLine()); //60
            int time3 = int.Parse(Console.ReadLine()); //13


            int totalTime = time1 + time2 + time3; //123

            int min = totalTime / 60; //123/60=2 (3)
            int sec = totalTime % 60; //123%60=3

            if (sec < 10)
            {
                Console.WriteLine($"{min}:0{sec}");
            }
            else
            {
                Console.WriteLine($"{min}:{sec}");
            }
        }
    }
}