public static void Main()
var a=int.Parse(Console.ReadLine());
var b=int.Parse(Console.ReadLine());
Console.WriteLine("Before: ");
Console.WriteLine("a= {0}",a);
Console.WriteLine("b= {0}",b);
Console.WriteLine("After: ");
Console.WriteLine("a= {0}",a);
Console.WriteLine("b= {0}",b);