Mask on UI touch C#

Hi, I would like to use mask with touch system and UI system. I thought if I put an mask I will not be able touch over mask image. Now I’m moving on red square area with function:

button.position = Input.GetTouch(0).position;


but I’m should be able to touch only on yellow circle or green shape.

I’m using unity 5.1.1f1 version.

Nevermind, solved.