求大神们帮忙看看错误在哪

use warnings;
use strict;






open(INFILE, "/Users/lizeshuo/Desktop/test2.txt") ||   die "Cannot open the newfile: $!\n";
open(OUTFILE, ">test3.txt") ||   die "Cannot open the newfile: $!\n";


my @a;


while () {
      chomp;
        
        @a = split;
        print OUTFILE "$a[1]"." ";
        print OUTFILE "$a[2]"." ";
}
exit;


open(INFILE, "/Users/lizeshuo/Desktop/test3.txt") ||   die "Cannot open the newfile: $!\n";


my @b;
my $number = 1;
my $c;
my @d


while () {
      chomp;
        
        @b = split;
        $c = $b[$number + 1] - $b[$number];
        push @d, $c;
        $number = $number + 2;
}
exit;