Arknights Welfare TG-1 Clear, Challenge Mode

To the Grinning Valley level TG-1, Bilateral Ventilation, Challenge Mode, cleared using only 6 Welfare operators.
This was a fairly simple level to clear. I tried to use my least built-up operators, but, because I focus on welfare operators, I don't have too many of those that aren't built up.
I made two kill zones of two melee operators each, right up at the enemy gate. This allowed me to have one healer and one sniper cover both zones. That was pretty much it. Enjoy.
Welfare operators are as defined at:
arknights.wiki...
wiki/Operator/Welfare.
Comments and advice are always appreciated.