use strict;
use warnings;

my @seq; # DNA sequence strings

do{
	print "Please enter DNA sequence (END to finish):";
	push @seq , $_=<STDIN>;  # First, assign whatever is read into $_, then append it to @seq
  } until $_ eq "END\n";

pop @seq;   # Remove the extra "END\n" entry;
chomp @seq; # Remove line endings on each entry

print "$_\n" 
  for  sort {length $a <=> length $b} @seq;