>perl -wMstrict -le
"my $ps  = pack 'N*', 11, 22, 33, 44, 55, 66;
 my $upk = '(x[N])3 N';
 my $n1   = unpack $upk, $ps;
 print qq{n1 $n1};
 my ($n2) = unpack $upk, $ps;
 print qq{n2 $n2};
"
n1 22
n2 44