using System;

    class Program

    {

        static void Main(string[] args)

        {

            double firstnum = double.Parse(Console.ReadLine());

            double secnum = double.Parse(Console.ReadLine());

            double thirdnum = double.Parse(Console.ReadLine());

            var solving = firstnum + secnum + thirdnum;

​

            TimeSpan t = TimeSpan.FromSeconds(solving);

            var compile = t.Minutes + ":" + t.Seconds;

​

​

            if (solving >= 0 && solving <= 59)

            {

                if (t.Seconds < 10)

                {

                    Console.WriteLine(t.Minutes + ":" + 0 + t.Seconds);

                }

                else

                {

                    Console.WriteLine(t.Minutes + ":" + t.Seconds);

                }

            }

            else if (solving >= 60 && solving <= 119)

            {

                if (t.Seconds < 10)

                {

                    Console.WriteLine(t.Minutes + ":" + 0 + t.Seconds);

                }

                else

                {

                    Console.WriteLine(t.Minutes + ":" + t.Seconds);

                }                

            }

            else if (solving >= 120 && solving <= 179)

            {

                if (t.Seconds < 10)

                {

                    Console.WriteLine(t.Minutes + ":" + 0 + t.Seconds);

                }

                else

                {

                    Console.WriteLine(t.Minutes + ":" + t.Seconds);

                }                

            }

        }

    }

​