2_2 pre_prod

program Project2;
{$APPTYPE CONSOLE}
uses
  SysUtils;

const
   ErrorMessage = 'Error! P should be natural number from 1 to 2147483647';
type
   TArray = array of Integer;

procedure EnterP(var P : Integer);
var
   Input : string;
   IsCorrect : Boolean;
begin
   IsCorrect := False;
   repeat
      try
         Writeln('Enter P');
         Readln(Input);
         P := StrToInt(Input);
         if P < 1 then
            Writeln(ErrorMessage)
         else
            IsCorrect := True
      except
         Writeln(ErrorMessage);
      end;
   until IsCorrect;
end;

function GetSumOfDividers(N : Integer) : Integer;
var
   i, Last, Sum: Integer;
begin
   Sum := 1;
   Last := Trunc(Sqrt(N));
   for i := 2 to Last do
      if N mod i = 0 then
         if i*i = N then
            Sum := Sum + i
         else
            Sum := Sum + i + (N div i);
   GetSumOfDividers := Sum;
end;

function IsPerfect(N : Integer) : Boolean;
begin
   if GetSumOfDividers(N) = N then
      IsPerfect := True
   else
      IsPerfect := False;
end;

procedure Main;
var
   P, i, x : Integer;
begin
   EnterP(P);
   i := 2;
   Writeln('All ''perfect'' numbers to ', P, ':');
   while i < P do
   begin
      if IsPerfect(i) then
         Writeln(i);
      Inc(i, 2);

   end;
   Readln;
end;

begin
   Main;
end.