Android Studio: com.support.android library problem

[BigCake]

I just tried to integrate Admob in my app.

 

Here are the steps I did:

1- Add maven repository in project level Gradle

2- Added in my build.gradle file

implementation 'com.google.android.gms:play-services-ads:15.0.1'

 

Right after adding, com.support.android appcomapt  threw error saying that libraries must use the exact same version specification

implementation 'com.android.support:appcompat-v7:28.0.0-alpha3'

^^ this one is causing the problem. I tried changing it to aplha1 and syncing the project but still no luck. The problem seems to be generating from maven repository

 

Here is the probable source of problem :

maven{url "https://maven.google.com"}

 

[BigCake]

Please anyone know how to fix it? I need to roll out update for my app real quickly for a bug fix. But this is error is giving warning that it may lead to run time crashes.