my $s = "foo. bar. foobar. foo bar.";
my $p = get_nsentences($s,2);  # $p = "foo. bar.";

print $p;
print "done\n";

## SUBS

# get n first sentences from a given string.
sub get_nsentences {
    my $source_txt = $_[0];
    my $ret_txt = "";

    # i know this looks twisted...
    for($i=$_[1]||1;$i>0 && length($source_txt);$i--) { $source_txt =~ s/([^\.]+\.)/(($ret_txt.=$1)&&"")/e; }
    return $ret_txt;
}