const
 s: string = 'this is a test of (very) simple) (program';

var first, second: byte;
begin
 repeat
   first := pos( '(', s );
   if first > 0 then
     begin
       second := pos(')', copy(s, first+1, length(s) - first)) + first;
       if second = first then second := length(s);
       if second > first then
         delete(s, first, second - first + 1);
     end;
 until first = 0;
 writeln( 's = ', s );
end.