How to find the centre position and display a message..

Hi can any one give solution i have 4 rectangular box which i place one above to other with some gap in between them. this 4 item are placed in large box. now i translate 4 item "up"inside the box like scrolling type. now i try when my translation stop the item which is in centre of large box display one mesg "i m in centre " can any one suggest how to do through code.

you want to find the center point of the 4 objects.

the center point of x number of objects is the sum of all individual centerpoints divided by
x

so

center of 2 boxes = box1.transform.position + box2.transform.position / 2