A variation on the theme of grep

my @ar = map { chomp; $_ } <DATA>;
print +(split /,/,
        $ar[ grep { /^(\d+)/ and $1 < 1006 } @ar ])[1], $/;

__DATA__
1001,choochoo
1002,candycane
1003,sockpuppet
1004,choochoo
1005,candycane
1006,sockpuppet6
1007,foo
1008,bar
[download]

This of course blindly assumes that you're data is a linear, contiguous set of numbers.
HTH

_________
broquaint