@date1 = ($dt[0], $dt[1], $dt[2], $dt[3], $dt[4], $dt[5]);

##</code><code>##

@date1 = @dt[0..5];

##</code><code>##

    chomp($line1);
    my @mg1 = split(/,/, $line1);
    my $line2 = <IN>;
    chomp($line2);
    my @mg2 = split(/,/, $line2);
    my $line3 = <IN>;
    chomp($line3);
    ...

##</code><code>##

my ($sum) = split /,/, $line;
for (2..12) {
   my ($val) = split /,/, <IN>;
   $sum += $val;
}