I accidentally did
apt-get remove python3 and didn't look at packages APT was about to remove.
Then Gnome Desktop Environment started to misbehave, I rebooted and it ended up in tty1 with no GUI.
I installed lightdm (just what found first in internet), it complained after I typed password
Failed to load session "cinnamon". I installed cinnamon. GUI appeared but it was, of course, Cinnamon not Gnome.
Then I googled more and installed gdm3 and gnome but I'm still in Cinnamon desktop and don't know how to get from it to Gnome.
sudo update-alternatives --config x-window-manager I don't see Gnome.
I tried to remove cinnamon and ended up with same
Failed to load session "cinnamon" on login.
Tried to purge and reinstall, but no success.
How do I get Gnome desktop environment back?