#include <cstdio>
#include <cmath>
#include <cstring>

using namespace std;

inline int iabs(int x) {
	return x > 0 ? x : -x;
}

inline int min(int x, int y) {
	return x < y ? x : y;
}

struct Pair {
	
	Pair(int x, int y) {
		first = x;
		second = y;
	}
	
	int first;
	int second;
};

int main() {
	
	int x = 42;
	int lastx = 20000;
	int y = 42;
	int lasty = 20000;
	int n = 42;

	bool rows[20000];
	bool cols[20000];
	bool diag1[40000];
	bool diag2[40000];

	char* a = new char[20000*20000];

	scanf("%d %d %d",&x,&y,&n);

	while(x || y || n) {


		if(lastx > 5000) {
						//printf("memset\n");
			memset( a, 0, 20000*20000);
		}else{
			for(int i = 0; i < lastx; i++) {
							//printf("else\n");
				 memset(a + i*20000, 0, lasty);
			}
		}
					//printf("mem ok\n");

		int free = 0;
		
		if(n > 0) {		

		


			memset( &rows, 0, 20000); 
			memset( &cols, 0, 20000); 
			memset( &diag1, 0, 40000); 
			memset( &diag2, 0, 40000); 

						//printf("ready\n");

			int kx;
			int ky;

			

			for(int i = 0; i < n; i++)		 {
				scanf("%d %d",&kx, &ky);
				kx -= 1;
				ky -= 1;

				// queen at a[kx*20000 + ky];

							//printf("input\n");

				char* ptr = a + kx*20000;
				if(!(rows[kx])) {
					memset(ptr, 1, y);
				}
				//printf("checkpoint0\n");

				ptr = a + ky;
				if(!(cols[ky])) {
								//printf("if ok\n");
					for(int i = 0; i < x; i++) {
						*ptr = 1;
						ptr += 20000;
					}
				}
			
				//printf("checkpoint1\n");

				if(!(diag1[kx - ky + 19999])) {

					ptr = a + kx*20000 + ky;
		
					for(int i = 0; i <= min(ky,kx); i++){
						*ptr = 1;
						ptr -= 20000 + 1;
					}
					//printf("checkpoint1a\n");
					ptr = a + kx*20000 + ky;
			
					for(int i = 0; i < min(y-ky, x - kx) ;i++){
						*ptr = 1;
						ptr += 20000 + 1;
					}
				}

				//printf("checkpoint2\n");

				if(!(diag2[kx+ky])) {

					ptr = a + kx*20000 + ky;
					
					for(int i = 0; i < min(kx + 1, y - ky) ;i++) {
						*ptr = 1;					
						ptr -= 20000 - 1;
					}

					ptr = a + kx*20000 + ky;			
		
					for(int i = 0; i < min(ky + 1, x - kx);i++){
						*ptr = 1;
						ptr += 20000 - 1;
					}
				}

					
				rows[kx] = true;
				cols[ky] = true;	
				diag1[ kx - ky + 19999 ] = true;
				diag2[ kx + ky ] = true;
			}

			//printf("checkpoint3\n");

		
			for(int i = 0; i < x; i++) {
				for(int j = 0; j < y; j++) {
					if(!(a[i*20000+j])) { 
						free++;
						/*printf(" ");
					}else {
						//printf("X");*/
					}
				}
				//printf("\n");
			}
		}else {
			free = x*y;
		}
		

		printf("%d\n",free);

		lastx = x;
		lasty = y;

		scanf("%d %d %d",&x,&y,&n);
	}

	return 0;
}