And this is my code

program ural1027;
const   ll='(*';
        rr='*)';

type    ts=ansistring;
var     s:ts;

procedure rd;
var     ch:char;
begin
 s:='';
 while not eof do
  begin
   read(ch);
   if (ch<>#13) and (ch<>#10) then s:=s+ch;
  end;
end;

procedure print(i:integer);
begin
 case i of
 0: write('NO');
 1: write('YES');
 end;
 halt;
end;

procedure dellr(var s:ts);
var  i,p,l:integer;


begin
 p:=pos(ll,s);
 l:=length(s);
 while p<>0 do
  begin
   i:=p+3;

   while (i<=l) and not ((s[i]=')') and (s[i-1]='*'))
    do inc(i);

   if (i>l) or (i=p+2) then print(0);

   delete(s,p,i+1-p);

   if s='' then print(1);
   p:=pos(ll,s);
   l:=length(s);
  end;

end;

procedure solve(s:ts);
var     p:integer;
        t:ts;
        ss:string;

 function cannot(t:ts):boolean;
 var    i,tot:integer;

 begin
  tot:=0;

  for i:=1 to length(t) do
   begin
    if s[i]='(' then inc(tot)
     else if s[i]=')' then dec(tot)
      else
       begin
        if not (s[i] in ['=','+','-','*','/','0'..'9',')','('])
            then exit(true);
       end;

    if tot<0 then exit(true)
     else if (tot>0) and (s[i]=' ') then exit(true);

   end;
  if tot<>0 then exit(true)
   else exit(false);
 end;

begin
 s:=s+' ';

 while s[1]=' ' do delete(s,1,1);
 p:=pos(' ',s);

 while (s<>'') and (p<>0) do
  begin

   t:=copy(s,1,p-1);
   if (pos('(',t)<>0) or (pos(')',t)<>0)
    then if cannot(t) then print(0);
   delete(s,1,p);

   while (s<>'') and (s[1]=' ') do delete(s,1,1);
   if s='' then break;
   p:=pos(' ',s);
  end;
end;

begin

 rd;

 dellr(s);
 solve(s);
 print(1);

end.


and if i remove the sentence
" if not (s[i] in ['=','+','-','*','/','0'..'9',')','('])
            then exit(true);"
I'll get WA#9

Who Can Tell Me WHY~~~~

Edited by author 27.10.2009 16:17

I think You should read it with the help of EndofLine or Readln.

Sorry EndofFile

 s:='';
 while not eof do
  begin
   read(ch);
   if ch>=' ' then s:=s+ch;
   if eoln then readln;
  end;

I change it like this
 but still WA#1, can you tell me how to read it correctly

You should

read(ch)
check if not eof
 and only then doing s:=s+ch;
          else break;