HELP! How to solve vector prod in CVX

My code are showing below:
“x = [2,3,2,4,5,2]
a = 1
variable r
minimize( prod(a + (x - r).^2) )

My purpose is to get the optimal r. It is kinda like doing a regression of x, and get the coefficient r. But it is not simple least square. The mathematical expression is as below:
min┬r⁡∏_(i from 1 to N)〖(a+(Xi - r)^2)〗

I got the error:
“Error using cvx/prod (line 84)
Disciplined convex programming error:
Invalid computation: prod( {convex} )
Error in Untitled (line 5)
minimize( prod(a + (x - r).^2) )”

I do not know how to solve this problem, please help me!!!

CVX is not the right tool for this problem. But if you just want to know the optimal value of r with this input data, it is 2.5038.