The question is kind of bullshit though. It’s meant to either get the other side to have an emotional response and say none or to be what you want perceived as a piece of shit and give a number. Let’s try it on another question.
How many child deaths are permissible before we ban bicycles? Cars? Jump rope? Pools? If it’s not 0, how dare you sir or ma’am. We’re talking about children here!
There is a reason certain buildings are off-limits unless it starts being used by the opposing force’s fighters. How would you fight a war against someone if they could just strike from an ambulance and then drive off, scott-free?
Also just want to throw out there that this type of thing is exactly what those who would use human shields want you to do. “Back off or we will put more civilians in front of us.” Then they will publicize the aftermath to help their propaganda war.