ANTLR Lexer Ambiguity

Ambig.g

grammar Ambig;

options {
	output=AST;
	ASTLabelType=CommonTree;
}

// --------------------------------------------------------------------------
ID	:	('a'..'z' | 'A'..'Z') ('0'..'9' | 'a'..'z' | 'A'..'Z' | ' ')*;
name	:	ID;

// --------------------------------------------------------------------------
PITCH	:	(('A'|'a') '#'?)
	|	(('B'|'b') '#'?) 
	|	(('C'|'c') '#'?);
note	:	PITCH;

main	:	name ':' note '\n'? { System.out.println($main.tree.toStringTree()); };

Ambig.java

import org.antlr.runtime.*;

public class Ambig {
    public static void main(String[] args) throws Exception {
        ANTLRInputStream input   = new ANTLRInputStream(System.in);
        AmbigLexer lex           = new AmbigLexer(input);
        CommonTokenStream tokens = new CommonTokenStream(lex);
        AmbigParser parser       = new AmbigParser(tokens);
        parser.main();
    }
}