my @arr=qw/A B C D E F/;
print join (",",@arr),"\n";

for (my $i=0;$i<=$#arr+1;$i++)	{
	for (my $j=$i+1;$j<=$#arr+2;$j++)	{
		my @tmp=@arr;
		splice @tmp,$i,0,'N';
		splice @tmp,$j,0,'N';
		print join (",",@tmp),"\n";
	}
}