i have a android application in which i have 4 activities, A,B,C and D

In Activity A is my login screen

if user is in B,C or in D and if user presses home button from B,C or D the app is getting closed and by default android home screen will come and if they again open that app,those only that Activity is opening from where they press Home button.

I want them to redirect to login page.

Note:i cant use onpause() and onstop() because i am moving from one activity to another continuously.

How should i do that ??