#define _USE_MATH_DEFINES
#include<stdio.h>
#include<string>
#include<iostream>
#include<cctype>
#include<cstdio>
#include<vector>
#include<stack>
#include<queue>
#include <algorithm>
#include<math.h>
#include<set>
#include<map>
#include<iomanip>

//#include<bits/stdc++.h>



using namespace std;


set<int>x[100005];
bool f[100005];

int main() {

	int w,h,n;
	cin>>w>>h>>n;
	
	
	
	int y=0;
	
	for(int i=0;i<n;i++){
		int a,b;
		cin>>a>>b;
		if(!f[b])y++;
		
		f[b]=1;
		x[a].insert(b);
	}
	long long int res=0;
	for(int i=1;i<=w;i++){
		if(x[i].size())res+=h-x[i].size();
		if(!x[i].size())res+=y;

		
	//cout<<res<<endl;
	}
	cout<<res<<endl;
	
	
	

	
	return 0;
}