my @letters = qw(d u n s c a e y t);
open(D,"/usr/share/dict/words") or die $!;

print f(@letters);

sub f {
#        1         2         3         4         5
#234567890123456789012345678901234567890123456789012345
my%h;$h{$_}++for@_;my@b;push @{$b[length]},$_ for grep{
#    6        7         8         9         0         1
#78901234567890123456789012345678901234567890123456789012
my%g=%h;$g{$_}--for/./g;!grep{$_<0}values%g}<D>;@{$b[-1]}
}