while (<DATA>)
{
    if ($_=~m#^([^\s]+)\s+([^\n]+)\n#)
    {
        push (@unordered, [$1,$2]);
    }
}

@ordered = sort {$a->[0] <=> $b->[0]} @unordered;

print "\n$_->[0]  = $_->[1]" for @ordered;

__DATA__
1260896 abadeno
972     achin00
402     astamen
181847  azeleke
134     b005376
1       b005824
[download]