my $range_start = 700;
my $range_end   = 1200;
my %out = ();
while (<>) {
    if ( /bn(\d+),/ && $1 >= $range_start && $1 <= $range_end ) {
        my $bn = $1;
        my ($when) = /^[^,]+,\w+\s+(\S+)\s/;
        push @{$out{$bn}}, $when;
    }
}
foreach my $ranger ( sort { $a <=> $b } keys %out ) {
    print "$ranger - ";
    print join ', ', @{$out{$ranger}};
    print "\n";
}