public static void Main()
int var1 = Convert.ToInt32(Console.ReadLine());
int var2 = Convert.ToInt32(Console.ReadLine());
int addResult = AddCalculator.Act(var1, var2);
Console.WriteLine(addResult);
Console.WriteLine("substitution is acting from Main");
int subVar1 = Convert.ToInt32(Console.ReadLine());
int subVar2 = Convert.ToInt32(Console.ReadLine());
var subResult = SubCalculator.Act(subVar1, subVar2);
Console.WriteLine(subResult);
int subVar3 = Convert.ToInt32(Console.ReadLine());
int subVar4 = Convert.ToInt32(Console.ReadLine());
var dilResult = DilCalculator.Act(subVar3, subVar4);
Console.WriteLine(dilResult);
Console.WriteLine("Trace END");
public static class AddCalculator
public static int Act(int a, int b)
Console.WriteLine("AddCalculator action");
public static class SubCalculator
public static int Act(int a, int b)
Console.WriteLine("SubCalculator action");
public static class DilCalculator
public static int Act(int a, int b)
Console.WriteLine("DilCalculator action");