public class Customer
{
    public string Password { get; set; }
    public string Stno { get; set; }
    public int value { get; set; }
    public bool Active { get; set; }
}

public class RequestContext
{
    public int VamValue { get; set; }
    public Customer student { get; set; }
}

public class ResponseContext
{
    public string Response { get; set; }
}

public abstract class GetVam
{
    protected readonly GetVam successor;
    
    public GetVam(GetVam _getVam)
    {
        this.successor = _getVam;
    }

    public abstract ResponseContext execute(RequestContext requestContext);
}

public class CheckUseractive : GetVam
{
    public CheckUseractive(GetVam _getVam) : base(_getVam)
    {
    }

    public override ResponseContext execute(RequestContext requestContext)
    {
        if (requestContext.student.Active == true)
        {
            return successor.execute(requestContext);
        }

        else
        {

            return new ResponseContext
            {
                Response = "student is inactive"
            };
        }
    }
}

public class ChechPassword : GetVam
{
    public ChechPassword(GetVam _getVam) : base(_getVam)
    {
    }

    public override ResponseContext execute(RequestContext requestContext)
    {
        if (requestContext.student.Password == "123")
        {
            return successor.execute(requestContext);
        }
        else
        {
            return new ResponseContext
            {
                Response = "invalid pass",
            };
        }
    }
}

public class ChechUserBedehkar : GetVam
{
    public ChechUserBedehkar(GetVam _getVam) : base(_getVam)
    {
    }

    public override ResponseContext execute(RequestContext requestContext)
    {
        if (requestContext.student.value < requestContext.VamValue)
        {
            return successor.execute(requestContext);
        }
        else
        {
            return new ResponseContext
            {
                Response = "you are dont permission"
            };
        }
    }
}

public class AssignVam : GetVam
{
    public AssignVam(GetVam _getVam) : base(_getVam)
    {
    }

    public override ResponseContext execute(RequestContext requestContext)
    {
        return new ResponseContext
        {
            Response = "value of vam: " + (requestContext.VamValue - requestContext.student.value).ToString();
        };
    }
}

partial class Program
{
    static void Main(string[] args)
    {
        Customer customer = new Customer()
        {
            Active = true,
            Password = "123",
            Stno = "111",
            value = 2000

        };

        RequestContext requestContext = new RequestContext()
        {

            student = customer,
            VamValue = 3000,
        };

        var GetVam = new CheckUseractive(new ChechPassword(new ChechUserBedehkar(new AssignVam(null))));
        var res = GetVam.execute(requestContext);
        Console.Write(res.Response);
        Console.ReadKey();
    }
}