A Flipkart delivery boy has to deliver the product to his customer. The delivery boy followed the below path to reach the customer from the Flipkart office. The delivery boy starts walking towards north. After walking 10 units he turns towards east. After walking 6 units he turns towards the north. After walking 4 units he turns west. Finally, after walking for 3 units he reached the customer house. If Flipkart office is at a point (3, -5) and customer house is at a point (x, y). The value of x + y is ___.