diff --git a/USolver.pas b/USolver.pas
index d47a893..47a8f64 100644
--- a/USolver.pas
+++ b/USolver.pas
@@ -36,27 +36,27 @@ type
     procedure Free;
     function GetDataFileName: string;
     function GetPuzzleName: string;
-    function GetResultPart1: Integer;
-    function GetResultPart2: Integer;
+    function GetResultPart1: Cardinal;
+    function GetResultPart2: Cardinal;
     property DataFileName: string read GetDataFileName;
     property PuzzleName: string read GetPuzzleName;
-    property ResultPart1: Integer read GetResultPart1;
-    property ResultPart2: Integer read GetResultPart2;
+    property ResultPart1: Cardinal read GetResultPart1;
+    property ResultPart2: Cardinal read GetResultPart2;
   end;
 
   { TSolver }
 
   TSolver = class abstract(ISolver)
   protected
-    FPart1, FPart2: Integer;
+    FPart1, FPart2: Cardinal;
   public
     procedure Init; virtual;
     procedure ProcessDataLine(const ALine: string); virtual; abstract;
     procedure Finish; virtual; abstract;
     function GetDataFileName: string; virtual; abstract;
     function GetPuzzleName: string; virtual; abstract;
-    function GetResultPart1: Integer; virtual;
-    function GetResultPart2: Integer; virtual;
+    function GetResultPart1: Cardinal; virtual;
+    function GetResultPart2: Cardinal; virtual;
   end;
 
   { TSolverEngine }
@@ -81,12 +81,12 @@ begin
   FPart2 := 0;
 end;
 
-function TSolver.GetResultPart1: Integer;
+function TSolver.GetResultPart1: Cardinal;
 begin
   Result := FPart1;
 end;
 
-function TSolver.GetResultPart2: Integer;
+function TSolver.GetResultPart2: Cardinal;
 begin
   Result := FPart2;
 end;