program LAB12;

{$APPTYPE CONSOLE}

uses
  Windows,
  SysUtils;

var
  Number, i, PlusOrMinus, Sum, EvenOrOdd : Integer;
  IsCorrect : Boolean;

begin
   SetConsoleCP(1251);
   SetConsoleOutPutCP(1251);
   Writeln('Çäðàâñòâóéòå, äàííàÿ ïðîãðàììà ñ÷èòàåò çíàêîïåðåìåííóþ ñóììó öèôð çàäàííîãî âàìè ÷èñëà');
   IsCorrect := False;
   repeat
      Writeln('Ââåäèòå ÷èñëî (äàííîå ÷èñëî äîëæíî áûòü íàòóðàëüíûì è äîëæíî áûòü íå áîëüøå 2147483647): ');
      try
         Readln(Number);
         IsCorrect := True;
      except
         on E: EInOutError do
            Writeln('Âû ââåëè íåâîçìîæíîå ÷èñëî! Ïîæàëóéñòà ââåäèòå ââåðíîå ÍÀÒÓÐÀËÜÍÎÅ ÷èñëî');
            end;
   until IsCorrect;
   EvenOrOdd := length(IntToStr(Number)) mod 2;
   Sum := 0;
      if EvenOrOdd = 0 then
         begin
         PlusOrMinus := -1;
         for i := 1 to Length(IntToStr(Number)) do
         begin
            Sum := Sum + PlusOrMinus * ((Number mod 10));
            Number := Number div 10;
            PlusOrMinus := PlusOrMinus * (-1)
         end;
         end
      else
         begin
         PlusOrMinus := 1;
         for i := 1 to Length(IntToStr(Number)) do
         begin
            Sum := Sum + PlusOrMinus * ((Number mod 10));
            Number := Number div 10;
            PlusOrMinus := PlusOrMinus * (-1)
         end;
         end;

   Writeln('Çíàêîïåðåìåííàÿ ñóììà öèôð çàäàííîãî âàìè ÷èñëà ðàâíÿåòñÿ ', IntToStr(Sum));
   Readln;
end.