def f1(y,x)
	if x<=y then
		return [y-x,0,0]
	else
		return [0,x-y,0]
	end
end
def f2(y,x,h)
	dy=h+1-y
	if x<dy then
		return [y+x,0,1]
	else
		return [h+1,x-dy,1]
	end
end
 
 
h,w=gets.split(" ").map{|e| e.to_i}
n=gets.to_i
hs1={}
hs2={}
n.times{
	y,x=gets.split(" ").map{|e| e.to_i}
	hs1[f1(y,x)]=1
	hs1[f2(y,x,h)]=1
	y2=y+2
	x2=x+1
	if y2<=h && x2<=w
		hs2[[y2,x2]]=0 if hs2.member?([y2,x2])==false	
		hs2[[y2,x2]]+=1
	end
	x2=x-1
	if y2<=h && 0<x2
		hs2[[y2,x2]]=0 if hs2.member?([y2,x2])==false	
		hs2[[y2,x2]]+=1
	end
}
#p hs1
hs3=hs2.select{|k,v|
	if v==2 then
		if hs1.member?(f1(k[0],k[1])) || hs1.member?(f2(k[0],k[1],h)) then
			false
		else
			true
		end
	else
		false
	end
}
puts hs3.size

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

OSA5CjQKMSAzCjcgMwoxIDUKMSA3

9 9
4
1 3
7 3
1 5
1 7