#!/usr/bin/perl
# usage: | test_ACGT_01.pl
use strict;
use warnings;
## no valued added (petty) to Loops try 2 : Y
#my $side = qr/(?:([ACGT])(?![^,]*\g{-1})){1,4}/;
## try 1 from Loops : N
#my $side = qr/(?:([ACGT])(?![^,]*\1))+/;
## try 2 from Loops : Y
my $side = qr/(?:([ACGT])(?![^,]*\g{-1}))+/;
##
while (<>) {
  chomp;
  print "$_ ". (/^$side,$side$/ ? 'Y' : 'N') . $/;
}
# eof