How to compare number with id of post in certain category

I found the solution

<?php 
$costumepost = "12709";
// args
$args = array(
    'numberposts'   => -1,
    'post_type'     => 'post',
    'cat'           => array(18),
    'meta_query'    => array(
        'relation'      => 'AND',
        array(
            'key'       => 'costumeid',
            'value'     => $costumepost,
            'compare'   => '='
        ),
    )
);

// query
$the_query = new WP_Query( $args );

?>
<?php if( $the_query->have_posts() ): ?>
    <?php while ( $the_query->have_posts() ) : $the_query->the_post(); ?>
        <?php echo get_post_meta($post->ID, 'artist', true); ?><br>
    <?php endwhile; ?>
<?php endif; ?>

<?php wp_reset_query();?>