for the given BNF above, convert it into a set of First rules.

for example

First(x) = { }

anything between single quotation is a terminal symbol

id and number are also terminal symbols

program ::- block block ::= declarat ion-list statement-list declarationlist ::- declaration statement.list : :- statement declaration ::- ' C' id ','id statement ::-assignment | print | do I if print::-'!' assignment ::- ref.id '-' expr r!expr do ::-', quarded.comman multop