I submit my program 20 times but I still get WA?
The problem is so simple but... I tried all tests written in the forum my program gives correct answer.

var
  a:array[1..10001] of char;
  ch:char;
  n:integer;
  skobka,comm:boolean;
  nsk:integer;
  i:integer;

procedure readdata;
begin
  n:=0;
  while not eof do
  begin
    inc(n);
    read(ch);
    a[n]:=ch;
  end;
end;

function check(ch:char):boolean;
begin
  if (ch in ['0'..'9']) or (ch in ['=','+','-','*','/']) then
  check:=true else check:=false;
end;

begin
  readdata;
  skobka:=false;
  comm:=false;
  for i:=1 to n do

  if (comm) and (a[i]='*') and (a[i+1]=')')  then
  begin
    comm:=false;
    inc(i);
  end         else

  if (not comm) and (a[i]='(') and (a[i+1]='*') then
  begin
    comm:=true;
    inc(i);
  end    else

  if comm then
  begin
  end          else

  if (not skobka) and (a[i]='(') then
  begin
    skobka:=true;
    nsk:=1;
  end            else

  if (skobka) and (a[i]=')') then
  begin
    dec(nsk);
    if nsk=0 then
    begin
      skobka:=false;
      nsk:=-maxint;
    end;
  end  else

  if (skobka) and (a[i]='(') then
  begin
    inc(nsk);
  end   else

  if ((skobka) and (not check(a[i]))) or
  ( (not skobka) and (a[i]='*') and (a[i+1]=')') and (not comm))
  then
  begin
    writeln('NO');
    halt;
  end  else

  if (nsk<0) and (nsk<>-maxint)then
  begin
    writeln('NO');
    halt;
  end;

  if (comm) or (skobka) then writeln('NO') else writeln('YES');
end.

On sample input yours outputs NO, correct is YES...

No, you are mistaken on sample test my program gives correct answer(YES)!