function tweet_button($content) {
        global $post;
        // Your Twitter ID goes here
        $twitterid = 'jan_dembowski';
        $tweetbutton = '<div class="tweet-button">';
        $tweetbutton = $tweetbutton . '<a href="http://twitter.com/share" class="twitter-share-button" data-url="' . get_permalink() .'" data-text="' . get_the_title() .'" data-count="horizontal" data-via="' . $twitterid . '">Tweet</a><script type="text/javascript" src="http://platform.twitter.com/widgets.js"></script>';
        $tweetbutton = $tweetbutton . '</div>';
        // $content = $content . $tweetbutton;
        $content = $tweetbutton . $content;
        return $content;
        }
add_filter('the_content', 'tweet_button');