def main():
   while True:
        username = input ("Enter Username: ")
        password = input ("Enter Password: ")

   if username == 'Filip' and password == 'XD' or "Miroslav" and "plusko12":
            import time
            time.sleep(1)
            print ("Login successful!")
            logged()
   else:
      print("STOP")


def logged():
    import time
    time.sleep(1)
    print ("Welcome to the Server")
    #Booting now
    print("Booting will begin shortly")
    import time
    time.sleep(3)
    print("Starting.................0%")
    # ... and there's more stuff in here
    quit(0)

main()

while True:
    username = input ("Enter Username: ")
    password = input ("Enter Password: ")

if username == 'Filip' and password == 'XD' or "Miroslav" and "plusko12":

if (username == 'Filip' and password == 'XD') or ("Miroslav" and "plusko12")
#                                                |---this is always True---|