#!/your/perl/here

use warnings;
use strict;

while (<DATA>)
{
	chomp;
	my $sort = join '', sort split '';
	( ( $sort =~ /^[afhmstw]+$/ ) # only these chars
	  and
	  ( $sort !~ /([afhmstw])\1/ ) ) # no repeats
	? print "<$_> OK\n"
	: print "<$_> Not OK\n";
}

__DATA__
smsa
smta
stmwhas

BADsmtaEXAMPLE

__END__
<smsa> Not OK
<smta> OK
<stmwhas> Not OK
<> Not OK
<BADsmtaEXAMPLE> Not OK