#include <stdio.h>
//#include <vector>
//#include <set>
//#include <pair>

using namespace std;

bool riadky[20005];
bool stlpce[20005];
bool hd[40010];
bool vd[40010];
//set< pair<int, int> > body;
//vector<int> veze_x;
//vector<int> veze_y;

int main(){
int x,y,n;
int a,b;	// suradnice veze
long long count;
scanf("%d %d %d", &x, &y, &n);
while ( ! (x==0 && y==0 && n==0) ) {

for (int i = 1; i <= x; ++i) riadky[i] = true;
for (int i = 1; i <= y; ++i) stlpce[i] = true;
for (int i = 1-y; i <= x-1; ++i) hd[i + 20005] = true;
for (int i = 2; i <= x+y; ++i) vd[i] = true;
//body.clear();
//veze_x.clear();
//veze_y.clear();
//cx = 0;
//cy = 0;

for(; n > 0; --n){
scanf("%d %d", &a, &b);
//veze_x.push_back(a);
//veze_y.push_back(b);
//if (riadky[a]){
riadky[a] = false;
//++cx;
//}
//if (stlpce[b]){
stlpce[b] = false;
//++cy;
//}
hd[a-b + 20005] = false;
vd[a+b] = false;
//printf("%d %d %d %d\n", a, b, a-b, a+b);
}

/*for (vector<int>::iterator vx = veze_x.begin(), vy = veze_y.begin(); vx != veze_x.end(); ++vx, ++vy){
int min, max, a = *vx, b = *vy;
pair<int, int> bod;
min = (a >= b)?b:a;
max = (a >= b)?a:b;
int k=0;
while (a-k > 0 && b-k > 0) {
if (riadky[a-k] && stlpce[b-k] && body.count(make_pair(a-k, b-k)) == 0) body.insert(make_pair(a-k, b-k));
++k; 
}
k = 0;
while (a+k <= x && b+k <= y) {
if (riadky[a+k] && stlpce[b+k] && body.count(make_pair(a+k, b+k)) == 0) body.insert(make_pair(a+k, b+k));
++k; 
}
k=0;
while (a+k <= x && b-k > 0) {
if (riadky[a+k] && stlpce[b-k] && body.count(make_pair(a+k, b-k)) == 0) body.insert(make_pair(a+k, b-k)); 
++k;

}
k=0;
while (a-k > 0 && b+k <= y) {
if (riadky[a-k] && stlpce[b+k] && body.count(make_pair(a-k, b+k)) == 0) body.insert(make_pair(a-k, b+k));
++k;
}
}*/

count = 0;
for (a = 1; a <= x; ++a){
for (b = 1; b <= y; ++b){
//printf("%d %d: %d %d %d %d\n", a, b, riadky[a], stlpce[b], hd[a-b + 20005], vd[a+b]);
if (riadky[a] && stlpce[b] && hd[a-b + 20005] && vd[a+b]) ++count;
}
}

//count = cy*x + cx*y - cy*cx;
printf("%lld\n", count);

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

return 0;
}