#!/usr/bin/perl -w

$DNA = <STDIN>;
chomp ($DNA);

@DNA = split ("", $DNA);
$lengthseq = scalar @DNA;
print "The length of the sequence is:\n", $lengthseq, "\n";

@nucleotideDNA = "";

#check if each element in array is nucleotide
foreach $nucleotide (@DNA){
	if ($nucleotide =~ /^[ATCG]+$/){
		push @nucleotideDNA, $nucleotide;
		}
	else {
		push @nonvalid, $nucleotide;
		}
	}