function blackandwhite_excerpt_length( $length ) {

    $excerpt = get_theme_mod('exc_length', '60');
    return $excerpt;

}

add_filter( 'excerpt_length', 'blackandwhite_excerpt_length', 999 );

function wpc_custom_excerpt($excerpt) {
    $excerpt = str_replace( "<p", "<p class=\"lead\"", $excerpt );
    return $excerpt;
}
add_filter('the_excerpt',  'wpc_custom_excerpt');

add_theme_support( 'post-thumbnails' );

function extrait_la_suite($more) {
global $post;
return &#039; <a href="'. get_permalink() . '" rel="nofollow">' . __( 'Lire la suite...', 'textdomain' ) . '</a>';
}
add_filter('excerpt_more', 'extrait_la_suite');