use strict;
my @frau = qw /bl ge gr br sw rt/;
my @mann = qw /ge bl bl br sw rt/;
my $paar;

my %fr = map { $_, 1 } @frau;
my %ma = map { $_, 1 } @mann;
for (keys %ma) {
    $paar++ if exists $fr{$_};
}
print "Paare: $paar\n";