yacc grammar for parsing simple expressions

Question

help me create a yacc grammar for parsing a simple expression, specifically this expression: 1;1;1;1;1;

It's important to consider some specifics:

1. Semicolon may be optional after the last '1'
2. The expression can be separated by a newline character, and the newline character can be placed either before or after the semicolon.

No matter what I try, I lack the skills; it's just becoming a puzzle. Here's my grammar:

%{
package main
%}

%union {
    token Token
}

%token<token> Number 

%%

start: expressions

expressions: Number
    | expressions NEWLINE
    | expressions SEMICOLON opt_Number
;

opt_Number: | Number

NEWLINE: '\n';
SEMICOLON: ';' ;

%%

It covers cases like 1;1;1;1, 1;1;1;1;, and 1;1;1\n;1, but it doesn't cover 1;1;\n1;1.

What am I missing?