use strict;
use warnings;

my %prns;

for (<DATA>)
{
    my ( $printer, $num, $cmd ) = split /:/;
    $prns{$num} = $printer;
}

my @ord = sort { $b <=> $a } keys %prns;

print "Highest numbered printer is $prns{shift @ord}\n";

__DATA__
M08_amvpss09_MEDIP :275:lp -damvpss09
M07_amvpss09_MEDIP :279:lp -damvpss09
M09_amvpss09_MEDIP :278:lp -damvpss09
M01_amvpss09_MEDIP :2:lp -damvpss09
M04_amvpss09_MEDIP :1000:lp -damvpss09