program Lab2Z2V31;

{$APPTYPE CONSOLE}

uses
  SysUtils;

procedure GetBin(var Num, Digit: Integer);
begin
   Digit := Num mod 2;
   Num := Num div 2;
end;

function ReverseBin(const Str: string): string;
var
   Index, Len: Integer;
begin
   Len := Length(Str);
   SetLength(Result, Len);
   for Index := Len downto 1 do
      ReverseBin[Len - Index + 1] := Str[Index];
end;

procedure Main();
const
   CMaxNatural = 2147483647;
   CMinNatural = 1;

var
   P,Num, Digit: Integer;
   Bin: String;
   IsCorrect: Boolean;

begin
   Write('Please, enter natural number to ', CMaxNatural,' : ');
   IsCorrect := false;
   repeat
      try
         Readln(P);
         if (P < CMinNatural) then
            Write('It is not a number from ', CMinNatural,' to ', CMaxNatural,' , please, enter valid number : ')
         else
            IsCorrect := true;
      except
         Write('Invalid input ! Please, enter natural number to ', CMaxNatural,' : ');
      end;
   until IsCorrect;

   Num := P;
   repeat
      GetBin(Num, Digit);
      Bin := Bin + IntToStr(Digit);
   until (Num < 2);
   if (P > CMinNatural) then
   begin
   Bin := Bin + '1';
   Bin := ReverseBin(Bin);
   end;

   Writeln(P,' in binary digit system equals : ', Bin);
   Readln;
end;

var
   IsContinue, IsCorrect: Boolean;
   Answer: Char;

begin
   Writeln('This program converts a natural number to binary digit system.');
   Main;
end.