Interstitial Ads Preload

I make a app wich has 7button on 1st screen and every button click open another screen.
now i want two show Intestitial ads on every 5th click of any button is it possible?
i have problem, when i open ads i preload interstitial ads and on button click i want to show ads on screen 1 but when i press button open another screen and then show interstitial ads behind screen 2 and its not appear please solve my problem.

use the this block to switch screen when the ad is closed then switch screen not before

but i use this block for preload interstitial ads
if i use this block for open onothor screen i have to set 7 different interstitial ads
user do not click on every button so my preloaded ads not shown