type
  Ordering = (_EQ, _LT, _GT);
  
  IEq<T> = interface
    function eequal(x, y: T): boolean;
    function notEqual(x, y: T): boolean;
  end;
  
  
  Eq<T> = abstract class(IEq<T>)
  public 
    
    function eequal(x, y: T): boolean; virtual;
    begin
      Result := not notEqual(x, y);
    end;
    
    function notEqual(x, y: T): boolean; virtual;
    begin
      Result := not eequal(x, y);
    end;
  end;
  
  
  IOrd<T> = interface(IEq<T>)
    function compare(x, y: T): Ordering;
    function less(x, y: T): boolean;
    function lessEqual(x, y: T): boolean;
    function greater(x, y: T): boolean;
    function greaterEqual(x, y: T): boolean;
    function mmin(x, y: T): T;
    function mmax(x, y: T): T;
  end;
  
  
  Ord<T, EqT> = abstract class(IOrd<T>)
  where EqT: IEq<T>, constructor;
  public 
    
    function compare(x, y: T): Ordering; virtual;
    begin
      var eqInst := __ConceptSingleton&<EqT>.&Instance;
      if eqInst.eequal(x, y) then
        Result := _EQ
      else if less(x, y) then
        Result := _LT
      else
        Result := _GT;
    end;
    
    function less(x, y: T): boolean; virtual;
    begin
      Result := compare(x, y) = _LT;
    end;
    
    function lessEqual(x, y: T): boolean; virtual;
    begin
      Result := compare(x, y) <> _GT;
    end;
    
    function greater(x, y: T): boolean; virtual;
    begin
      Result := compare(x, y) = _GT;
    end;
    
    function greaterEqual(x, y: T): boolean; virtual;
    begin
      Result := compare(x, y) <> _LT;
    end;
    
    function mmin(x, y: T): T; virtual;
    begin
      Result := lessEqual(x, y) ? x : y;
    end;
    
    function mmax(x, y: T): T; virtual;
    begin
      Result := lessEqual(x, y) ? y : x;
    end;
    
    function eequal(x, y: T): boolean; virtual;
    begin
      var eqInst := __ConceptSingleton&<EqT>.&Instance;
      Result := eqInst.eequal(x, y);
    end;
    
    function notEqual(x, y: T): boolean; virtual;
    begin
      var eqInst := __ConceptSingleton&<EqT>.&Instance;
      Result := eqInst.notEqual(x, y);
    end;
  end;
  
  
  Eq_integer = class(Eq<integer>, IEq<integer>)
  public 
    
    function eequal(x, y: integer): boolean; override;
    begin
      Result := x = y;
    end;
  end;
  
  
  Ord_integer<EqT> = class(Ord<integer, EqT>, IOrd<integer>)
  where EqT: IEq<integer>, constructor;
  public 
    
    function compare(x, y: integer): Ordering; override;
    begin
      if self.eequal(x, y) then
        Result := _EQ
      else if x < y then
        Result := _LT
      else
        Result := _GT;
    end;
  end;


function Max3<T, OrdT>(v1, v2, v3: T): T;
  where OrdT: IOrd<T>, constructor;
begin
  var ordInst := __ConceptSingleton&<OrdT>.&Instance;
  
  Result := ordInst.mmax(v1, ordInst.mmax(v2, v3));
end;


begin
  writeln(Max3&<integer, Ord_integer<Eq_integer>>(1, 2, 3))
end.