Count the boots and divide by two.
Possible approximation. With the large number of injuries from land mines, might be more like “divide by 1.6”, and being Afghans, also need to count sandals. I wonder if the toilets in tunnels do not face away from Mecca. We deliberately put our toilet there with the backside toward Mecca to spite their satanic religion. I once saw a long, narrow bathroom with the toilet the wrong way.