using System;

public class Program

{

    public static void Swap(ref int x,ref int y)

    {

        int temp;

        temp = x;

        x = y;

        y = temp;

        Console.WriteLine("In Swap method: "+

                         "a={0}; b={1}\n",x,y);

        return ;

    }

    public static void Main()

    {

        int a,b =0;

        Console.Write("Nhap so nguyen a: ");

        a = int.Parse(Console.ReadLine());

        Console.Write("Nhap so nguyen b: ");

        b = int.Parse(Console.ReadLine());

        Console.WriteLine("\nBefore swapping: "+

                          "a={0}; b={1} \n",a,b);

        Swap(ref a, ref b);

        Console.WriteLine("After swapping: "+

                          "a={0}; b={1} \n",a,b);

        Console.ReadLine();

    }

}