How fast can you do it ? Part 2 - A warmup chase

Two opposite vertices of a square are $(5,4) , (1,-6)$

Find the other two vertices .

Note:- Enter the answer as the product of the sum of the coordinates of the two points. For exmple:-

If the answer is => $(2,3),(-5,-4)$

Then enter the answer as $(2+3)\times(-5-4)$