[Beginner Question]A question about yacc & lex

Hi team,

now I'm learning the yacc & lex to understand the principle of the postgres's parser.

And I write a test program as this:

/*
    array.l
        Array program
    Wen Yi
*/
%option noyywrap
%option noinput

%{
#include <stdlib.h>
#include "y.tab.h"
%}

%%

[0-9]+ { yylval.number = atoi(yytext); return NUMBER;}

\n { return END; }

%%

/*
    array.y
        Array program
    Wen Yi
*/

%{
#include <stdio.h>
int yylex();
int yyerror(char *s);
%}
%token NUMBER
%token END
%union
{
    int number;
}

%%

end:
| array_list END { printf ("= %d\n", $1.number); }

array_list: array { $$.number = $1.number; }

array: number { $$.number = $1.number; }
| array number { $$.number = $1.number + $2.number; }

number: NUMBER { $$.number = $1.number;  }

%%

int main(int argc, char *argv[])
{
    yyparse();
}
int yyerror(char *s)
{
    puts(s);
}

The running result is this:

[beginnerc@bogon code]$ ./a.out
1 2 3 4 5 6
     = 21
1
syntax error

I don't know  why are there many extra spaces in the output, and why the error message 'syntax error' is showed.