Add brackets to grammar for safety

psGrammar/challenge/team2/bill.jsgf

@@ -2,8 +2,8 @@
 grammar bill;
 public <command> = ( <setupbill> | <thatscorrect> | <correction> );
 
-<setupbill> = (([tiago] [please]) ((set up the ( bill | check )) | (could i have the ( bill | check )) | (i ( would like | want ) to pay) | (can i pay) | bill) [now] [please]);
-<thatscorrect> = ( yes | ([yes] you got that ( right | correct )) | ([yes] that is ( right | correct )) );
+<setupbill> = (([tiago] [please]) (((set up the) ( bill | check )) | ((could i have the) ( bill | check )) | (i ( (would like) | want ) to pay) | (can i pay) | bill) [now] [please]);
+<thatscorrect> = ( yes | ([yes] (you got that) ( right | correct )) | ([yes] (that is) ( right | correct )) );
 <correction> = ([[no] ((i ordered) | (there are))] <drink> [[and] <drink>] [[and] <drink>]);
 
 <drink> = ([ (((a | one) [(bottle | cup | can) of] )) | ((two | three) [(bottles | cups | cans) of]) ] ( coke | malz | lemonade | water | (ice tea) | coffee ));