Lenovo y50 PCI-E

Hello, I'd like to ask 2 questions: How many PCI-E slots has Lenovo y50? I don't have this laptop, but I want to buy it, once. And I found that external GPU can be added thruth PCI-E, but most laptops has only 1 and it's used for Wifi. So how many PCI-E slots has Lenovo y50? Also, how can be...