#include <cstdio>
#include <cstdlib>
#include <vector>
#include <iostream>
#include <algorithm>
#include <cstring>
using namespace std;

#define BASE 64LL

int T[1<<17];

int numone(int a){
	int sum=0;
	while(a>0){
		sum+=a%2;
		a/=2;
	}
	return sum;
}

void create_table(){
	int Max = 1<<16;
	for(int i=0;i<Max;i++){
		T[i]=numone(i);
	}
}


int getNumOne(unsigned long long one){
	int sum=0;
	unsigned short int *A=(unsigned short int*)&one;
	for(int i=0;i<4;i++){
		sum+=numone(A[i]);
	}
	return sum;
}

int X,Y,N;

int Q[4][22222];

unsigned long long B[3][320];

int main(){

	create_table();
	scanf(" %d %d %d",&X,&Y,&N);
	while(X>0||Y>0||N>0){
		for(int i=0;i<3;i++)memset(B[i],0,320*sizeof(unsigned long long));
		for(int i=0;i<N;i++){
			scanf(" %d %d",&Q[0][i],&Q[1][i]);
			Q[0][i]--;
			Q[1][i]--;
			Q[2][i]=Q[0][i]-Q[1][i];
			Q[3][i]=Q[0][i]+Q[1][i]-Y+1;
		}

		for(int i=0;i<4;i++)sort(Q[i],Q[i]+N);
		/*	for(int i=0;i<4;i++){
			for(int j=0;j<N;j++){
			cout<<Q[i][j]<<" ";

			}cout<<endl;
			}*/


		int number=0;

		int newY=Y/BASE+1LL;
		int lastSegment = Y/BASE;
		int lastOffset = Y%BASE;
		//nastav na -1
		//

		for(int i=0;i<N;i++){	
			B[0][Q[1][i]/BASE]|=1LL<<(Q[1][i]%BASE);
		}

		int pX=0;
		int pKles=0;
		int pStup=0;
		while(pKles<N&&Q[3][pKles]<0){
			int a=Y+Q[3][pKles];
			B[2][a/BASE]|=1LL<<(a%BASE);
			pKles++;
		}
		while(pStup<N&&Q[2][pStup]<0){
			int a=-Q[2][pStup]-1LL;
			B[1][a/BASE]|=1LL<<(a%BASE);
			pStup++;
		}

		for(int i=0;i<X;i++){
			//Urob posun
			//posun 1
			unsigned long long carry=0;
			for(int j=0;j<newY;j++){
				unsigned long long K=(B[1][j]<<1LL)+carry;
				if(B[1][j] & (1LL<<(BASE-1LL)))carry=1;
				else carry=0;
//				K%=1LL<<BASE;
				B[1][j]=K;

			}
			B[1][lastSegment]&=(1LL<<lastOffset)-1LL;
			//posun 2
			carry=0;
			for(int j=newY-1;j>=0;j--){
				unsigned long long K=(B[2][j]>>1LL)+(carry<<(BASE-1LL));
				//			cout<<B[2][j]<<" "<<K<<" "<<carry<<" -- ";
				if(B[2][j]&1)carry=1;
				else carry=0;
				B[2][j]=K;
			}
			//pridaj nove
			if(pStup<N&&(i==Q[2][pStup])){
				B[1][0]|=1;
				pStup++;
			}
			while(pKles<N&&i>Q[3][pKles])pKles++;
			if(pKles<N&&(i==Q[3][pKles])){
				//			cout<<"*";
				B[2][(Y-1LL)/BASE]|=1LL<<((Y-1LL)%BASE);
				pKles++;
			}
			while(pX<N&&i>Q[0][pX])pX++;
/*			cout<<i<<":       ";
			for(int j=0;j<Y;j++){
				int seg=j/BASE;
				int off=j%BASE;
				int A=B[0][seg]|B[1][seg]|B[2][seg];
				if(pX<N&&Q[0][pX]==i){
					cout<<" 1";
				}else
					cout<<" "<<((A&(1<<off))>0);
			}cout<<"             ";
			cout<<pX<<" "<<Q[0][pX];
			int n=0;	
			for(int j=0;j<newY;j++){
				n += getNumOne(B[0][j]|B[1][j]|B[2][j]);
			}
			cout<<"               "<<n;
			cout<<endl;*/
			if(pX<N&&Q[0][pX]==i){
				pX++;
				number+=Y;
				continue;//nescitavame
			}
			//spocitaj jednotky
			for(int j=0;j<newY;j++){
				number += getNumOne(B[0][j]|B[1][j]|B[2][j]);
			}
		}

		printf("%d\n",X*Y-number);

		scanf(" %d %d %d",&X,&Y,&N);
	}
}