my @words = (
    # WortA:
    { map {$_ => 1} qw/haus tier garten/ },
    # WortB:
    { map {$_ => 1} qw/straße auto reifen/ },
    # WortC:
    { map {$_ => 1} qw/pc monitor tastatur maus/ },
);

my @sentence = qw/haus auto maus/;
my $legal    = 1;

for my $i (0 .. $#sentence) {
    unless (exists $words[$i]->{$sentence[$i]}) {
        $legal = 0;
        last;
    }
}

print $legal ? "legal\n" : "illegal\n";