#include <iostream>
#include <vector>
#include <cstdio>
#include <string>
#include <cstring>
using namespace std;
#define FOR(i, to) for(int i = 0 ; i < to ; ++i)

int dia1[80000],dia2[100000];
int stlpec[20000],riadok[20000];
int R,C,N;
long long res;

int gd1(int x, int y){ return y + R-1 - x;}
int gd2(int x, int y){ return y + x;}

int main(){
	while(true){
		scanf("%d %d %d ",&R,&C,&N);
		if (R == 0) break;
		res = 0;
		FOR(i,R){ riadok[i] = 0; }
		FOR(i,C){ stlpec[i] = 0; }
		FOR(i,R+C+47){ dia1[i] = 0; dia2[i] = 0;}
		FOR(i,N){
			int x,y;
			scanf("%d %d ",&x,&y);
			x--; y--;
			riadok[x] = 1;
			stlpec[y] = 1;
			dia1[ gd1(x,y) ] = 1;
			dia2[ gd2(x,y) ] = 1;
		}
		FOR(i,R){
			if (riadok[i] == 1) continue;
			FOR(j,C)if (stlpec[j] == 0){
				if ( dia1[gd1(i,j)] == 1) continue;
				if ( dia2[gd2(i,j)] == 1) continue;
				res++;
			}
		}
		printf("%lld\n",res);
	}
	return 0;
}