#include <iostream>
 using namespace std;
 





int main() {
	
	
	
	 int X = 0;
	 int Y = 0;
	 int N = 0;
	 int * * sachovnice;
	 cin >> X  >> Y  >> N;
	
	while ( X!=0 && Y!=0 && N!=0) {
	sachovnice = new int*[X];
	
	
	for (int i = 0; i < X; i++) {
		sachovnice[i] = new int[Y];
		for(int j = 0; j < Y; j++) {
			sachovnice[i][j] = 0; // prazdne pole
		}
	}		
	
	int xk = 0;
	int yk = 0;
	int i = 0;
	int j = 0;
	
	
	 for (int k=0; k < N; k++) {
		 
		 cin >> xk >> yk;
		 xk--; yk--;
		 sachovnice[xk][yk]  = 1; // zaplnene
		 
		 for (i = 0; i < Y; i++) {
			 sachovnice[xk][i] = 1;
		 }
		 
		 for (i = 0; i < X; i++) {
			 sachovnice[i][yk] = 1;
		 }
		 
		 for(i = xk, j =yk; i < X && j < Y; i++,j++) 	{
			 sachovnice[i][j] = 1;
		 }
		 
		 for( i = xk, j =yk; i >= 0 && j >=0; i--,j--) 	{
			 sachovnice[i][j] = 1;
		 }
		 
		 for( i =xk, j =yk; i < X && j >=0; i++,j--) 	{
			 sachovnice[i][j] = 1;
		 }
		 
		 for(i = xk, j =yk; i >= 0 && j < Y; i--,j++) 	{
			 sachovnice[i][j] = 1;
		 }
	 }
	 cin >> xk >> yk >> i;
	 
	 int count = 0;
	 for (i = 0; i < X; i++) {
		for( j = 0; j < Y; j++) {
			if (sachovnice[i][j] == 0) {
				count++;
			}
		}
	}

	 cout << count << endl;
	
	cin >> X  >> Y  >> N;
}
	 return 0;
}