namespace lab1
{
    class Program
    {
        static int nod (int a, int b)
        {
            if (a == b)
                return a;
            else
            {
                if (a > b)
                    return nod(a-b, b);
                else
                    return nod(a, b-a);
            }
        }
       static void Main(string[] args)
        {
            try
            {
                Console.Write("a= ");
                int a = int.Parse(Console.ReadLine());
                Console.Write("b= ");
                int b = int.Parse(Console.ReadLine());
 
                    Console.Write("NOD(a,b)={0}",nod(a,b));
                Console.ReadLine();
            }
            catch (System.Exception ex)
            {
                Console.WriteLine(ex.Message);
                Console.ReadLine();
            }
 
        }
 
    }
}