Test

program Project1;

{$mode objfpc}{$H+}

uses
  {$IFDEF UNIX}{$IFDEF UseCThreads}
  cthreads,
  {$ENDIF}{$ENDIF}
  Classes
  { you can add units after this };
const st = 1; ed = 30;
function fact(n: Integer): Integer;
begin
     if (n = 0) or (n = 1) then fact := 1
     else fact := n * fact(n-1);
end;

function sum(n: Integer): real;
var
  i: Integer;
  suma: real;
begin
     suma := 0;
     for i := 1 to n do
         suma := suma + (1 / fact(i));
     sum := suma;
end;
var
  am: Integer;
  f: TextFile;
begin
     AssignFile(f, 'tty.txt');
     write('Vvedit6: ');
     readln(am);
     if (am < st) or (am > ed) then writeln('Veluke chislo!')
     else
       begin
            rewrite(f);
            writeln(f, 'Sum: ', sum(am));
            CloseFile(f);
       end;
end.