#include <iostream>
#include <math.h>
using namespace std;

int main(){
	int x, y, n;
	while(1){
		int count = 0;
		cin >> x >> y >> n;
		if(x==0 & y==0 & n==0) break;
		// bool board[x][y];
		bool xes[x];
		bool yns[y];
		bool ldiag[x+y-1];
		bool pdiag[x+y-1];
		for(int i = 0;i<x;i++){
			xes[i]=false;
		}
		for(int i = 0;i<y;i++){
			yns[i]=false;
		}
		for(int i = 0;i<(x+y-1);i++){
			ldiag[i]=false;
			pdiag[i]=false;
		}

		/*for(int i = 0; i< x; i++){
			for(int j=0; j<y;j++){
				board[x][y] = false;
			}
		}*/

		while(n>0){
			n--;
			int inx, iny, invx;
			cin >> inx >> iny;
			inx--;
			iny--;
			invx = x-1-inx;
			xes[inx] = true;
			yns[iny] = true;
			ldiag[inx+iny] = true;
			pdiag[invx+iny] = true;

			//cout <<	inx << " " << iny << " " << inx+iny-1 << " " << invx+iny-1 << endl;
			
		}	

		/*for(int i = 0;i<x;i++){
			if(xes[i]) cout << i << endl;		
		}
		for(int i = 0;i<y;i++){
			if(yns[i]) cout << i << endl;
		}
		for(int i = 0;i<(x+y-1);i++){
			if(ldiag[i]) cout<< i << endl;		}	
		for(int i = 0;i<(x+y-1);i++){
			if(pdiag[i]) cout <<  i << endl;
		}*/



		for(int i = 0; i< x;i++){
			for(int j=0;j<y;j++){

				/*cout << i << " " << j << " ";
				cout << i+j << " ";
				cout << x-i+j << endl;*/
				//cout << " |"<< ldiag[4] << " " << pdiag[7];
				if(!(xes[i] | yns[j] | ldiag[i+j] | pdiag[x-i+j-1])) {
					count++;
				}
			}
		}
		
		cout << count << endl;

	}
	return 0;
}