c:\@Work\Perl\monks>perl -wMstrict -le
"use constant K => 234_565;
 ;;
 my $s = 'xxx' . 'a' x K . 'yyy';
 print substr $s, 0, 10;
 print substr $s, -10;
 print length $s;
 ;;
 use constant MAX => 32_760;
 ;;
 use integer;
 my $n = K / MAX;  print $n;
 my $m = K % MAX;  print $m;
 ;;
 my ($t) = $s =~ m{ xxx ((?: .{${ \MAX }}){$n} .{$m}) yyy }xms;
 print substr $t, 0, 10;
 print substr $t, -10;
 print length $t;
"
xxxaaaaaaa
aaaaaaayyy
234571
7
5245
aaaaaaaaaa
aaaaaaaaaa
234565