{$IFDEF DEBUG}
Uses CalcTime, Debug;
{$ENDIF}
label a;
var
  STACKPos : word;
  STACK : array [1..10010] of set of (Skobki, Comment, Txt);
  c, cnext : char;

begin
  c := #0; STACKPos := 1;
  STACK [STACKPos] := [];
  repeat Read (cnext) until cnext > #13;
  while not (cnext = #26) do begin
    c := cnext;
    repeat Read (cnext) until cnext in [#26, #32..#255];
    if (c = '(') then begin
      Inc (STACKPos);
      if cnext = '*' then begin
        STACK [STACKPos] := [Comment];
      end else begin
        STACK [STACKPos] := [Skobki];
      end;
    end;
    if not
      (c in ['=', '+', '-', '*', '/',
             '0'..'9', '(', ')']) then begin
      Include (STACK [STACKPos], Txt);
    end;
    if (cnext = ')') then begin
      if ((c = '*') and (STACK [STACKPos] = [Comment, Txt])) or
        ((STACK [STACKPos] = [Comment]) or
        (STACK [STACKPos] = [Skobki])) then begin
          Dec (StackPos);
          if StackPos = 0 then goto a;
        end else if not (STACK [STACKPos] = [Comment, Txt]) then begin
a:        WriteLn ('NO');
          Halt;
        end;
    end;
  end;
  if (STACKPos = 1) {and (STACK [STACKPos] = [Txt])} then begin
    WriteLn ('YES');
  end else WriteLn ('NO');
end.