Help with php function

Hi I’m trying to make a function to add a woocommerce sort by drop down appear on a specific shop page (the main shop page only (id=655)).

function addDropDown()
	{

		global $wp_query;
		$pageid = $post->ID;

		if($pageid=655)
		{
			add_action( 'woocommerce_before_main_content', 'woocommerce_catalog_ordering', 20 );
		}
	}
	add_action('init', 'removeDropDown');

I use add_action( 'woocommerce_before_main_content', 'woocommerce_catalog_ordering', 20 ); to add the drop down menu to the shop pages. However it appears on the shop page and the single product page.

Even if i change if($pageid=655) to if($pageid=6) the drop down appears on both the shop page and single product page!

Help please!