How to accept Xcode license?

I want to install a C based toolbox on Matlab software. To do this, I should install GCC compiler. I think I have done that already. And also I have Xcode too.

To setup the toolbox I need to write "mex -setup;" in matlab command window. I've got the following warning and dont know who to solve it:

Warning: Xcode is installed, but its license has
not been accepted. Run Xcode and accept its
license agreement.

Error using mex
No supported compiler or SDK was found. For
options, visit 
http://ift.tt/1wKtwYA.