using System;

public class Change 

{

         public long coin2 = 0;

         public long bill5 = 0;

         public long bill10 = 0;

}   

​

public class Program

{

    public static Change OptimalChange(long s) {

​

        //test pour un montant minimum pour de la monnaie

        if((s < 5) && ((s%2) != 0))

        {

            return null;

        }

        Change change = new Change();

        change.bill10 = s/10;

        s = s%10;

        change.bill5 = s/5;

        s = s %5;

        if ((s %2) != 0)

        {

            if(change.bill5 == 0)

            {

                change.bill10 -= 1;

                change.bill5 += 2;

            }

            change.bill5 -=1 ;

            s += 5;

        }

​

        change.coin2 = s /2;

        return change;

    }

​

    public static void Main()

    {

        //long nbTest = 31;

        long nbTest = 1;

        //long nbTest = 3;

        //long nbTest = 9223372036854775803;

        //long nbTest = 58;

        Change monney = OptimalChange(nbTest);

        Console.WriteLine(nbTest);

        if(monney != null)

        {

            Console.WriteLine("10 : "+ monney.bill10);

            Console.WriteLine("5 : "+ monney.bill5);

            Console.WriteLine("2 : "+ monney.coin2);

        }

        else

            Console.WriteLine("null");

    }

}