Type TPositiveNumber = 0..$FFFFFF; //Int64, QWord, etc.

Type TFraction = Packed Record //Wygodniej byłoby operować na klasach, no ale...
                  Numerator, Denominator: TPositiveNumber;
                 End;

(* ============================ *)

Function IntToStr(I: Integer): String;
Begin
 Str(I, Result);
End;

Function NWW(A, B: TPositiveNumber): TPositiveNumber;
Var C, D: TPositiveNumber;
Begin
 D := A*B;
 While (B <> 0) Do
 Begin
  C := A mod B;
  A := B;
  B := C;
 End;
 Result := D div A;
End;

(* ============================ *)

Function Fraction(Num, Den: TPositiveNumber): TFraction;
Begin
 Result.Numerator   := Num;
 Result.Denominator := Den;
End;

Procedure SameDenominator(var F1, F2: TFraction);
Var Mul1, Mul2, NW: TPositiveNumber;
Begin
 NW   := NWW(F1.Denominator, F2.Denominator);
 Mul1 := NW div F1.Denominator;
 Mul2 := NW div F2.Denominator;

 F1.Numerator   := F1.Numerator*Mul1;
 F2.Numerator   := F2.Numerator*Mul2;
 F1.Denominator := NW;
 F2.Denominator := NW;
End;

Function Sub(F1, F2: TFraction): TFraction;
Begin
 Result := Fraction(0, 0);

 if (F1.Denominator = F2.Denominator) Then
  Result := Fraction(F1.Numerator-F2.Numerator, F1.Denominator) Else
 Begin
  SameDenominator(F1, F2);

  Result := Sub(F1, F2);
 End;
End;

Function Add(F1, F2: TFraction): TFraction;
Begin
 Result := Fraction(0, 0);

 if (F1.Denominator = F2.Denominator) Then
  Result := Fraction(F1.Numerator+F2.Numerator, F1.Denominator) Else
 Begin
  SameDenominator(F1, F2);

  Result := Add(F1, F2);
 End;
End;

Function toString(F1: TFraction): String; //...np.to powinna być metoda klasy, etc, no ale...
Begin
 Result := IntToStr(F1.Numerator)+'/'+IntToStr(F1.Denominator);
End;

Var F1, F2: TFraction;
Begin
 F1 := Fraction(1, 9);
 F2 := Fraction(1, 5);
 Writeln(toString(Sub(F1, F2)));
End.