Woocommerce – add products automatically to cart

HEllo,
I want to add a product with ID 11 automatically to the cart when two of products with ID 22 are already in cart.
And if four products 22 are in cart, then two producs 11 should be added automatically to cart and so on.
Having this script:

add_action( 'init', 'add_product_to_cart' );
function add_product_to_cart() {
  if ( ! is_admin() ) {
		global $woocommerce;
		$product_id = 11;
		$found = false;
		$cart_total = 30;

		if( $woocommerce->cart->total >= $cart_total ) {
			//check if product already in cart
			if ( sizeof( $woocommerce->cart->get_cart() ) > 0 ) {
				foreach ( $woocommerce->cart->get_cart() as $cart_item_key => $values ) {
					$_product = $values['data'];
					if ( $_product->id == $product_id )
						$found = true;
				}
				// if product not found, add it
				if ( ! $found )
					$woocommerce->cart->add_to_cart( $product_id );
			} else {
				// if no products in cart, add it
				$woocommerce->cart->add_to_cart( $product_id );
			}
		}
	}
}