Prestashop - 1.7.4.2 - double if statement

I'm facing a (new) problem with prestashop 1.7.4.2. I want to check if certain product ID is in cart before to allow customer proceeds checkout. If not, I want to display an alert. It works like this : {if !Context::getContext()->cart->containsProduct(784)} message {/if}

• I want to add a second if statement to check if there is a certain number of products in cart.

If there is less than xx products in cart AND/OR if cart containsProduct(784), I want to display message.

Any help will be greatly appreciated ! Thanks a lot & cheers !

Camille.