求dalao，为什么RE？？？（P）

type
 stack=record
        data:array[1..100] of real;
        top:0..100;
       end;
var
 s:stack;
 ch:char;
 i:longint;
 x:real;
 a:array[1..30] of char;
function pop(var s:stack):real;
begin
 pop:=s.data[s.top];
 s.top:=s.top-1;
end;
procedure push(var s:stack;x:real);
begin
 s.top:=s.top+1;
 s.data[s.top]:=x;
end;
begin
 i:=0;
 repeat
  i:=i+1;
  read(a[i]);
 until a[i]='@';
 s.top:=0;
 i:=1;
 ch:=a[i];
 while ch<>'@' do
  begin
   case ch of 
    '0'..'9':begin
     x:=0;
     while ch<>' ' do
      begin
       x:=x*10+ord(ch)-ord('0');
       i:=i+1;
       ch:=a[i];
      end;
     end;
    '+':x:=pop(s)+pop(s);
    '-':begin
     x:=pop(s);
     x:=pop(s)-x;
     end;
    '*':x:=pop(s)*pop(s);
    '/':begin
     x:=pop(s);
     x:=pop(s)/x;
     end;
   end;
 push(s,x);
 i:=i+1;
 ch:=a[i];
 end;
writeln(pop(s));
end.