my %sequence = (
   1345 => 10,
   123  => 20,
   500  => 30,
);

##</code><code>##

$sequence{901} = 40;

##</code><code>##

$sequence{$id} = $score;

##</code><code>##

print "$_ => $sequence{$_}\n" for sort {$a<=>$b} keys %sequence;