#include <iostream>
#include <string>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <vector>
#include <cmath>
#include <cstdlib>
#include <queue>
#include <stack>
#include <iomanip>

using namespace std;

#define REP(i, n) for(ll i = 0;i < n;i++)
#define REPR(i, n) for(ll i = n;i >= 0;i--)
#define FOR(i, m, n) for(ll i = m;i < n;i++)
#define FORR(i, m, n) for(ll i = m;i >= n;i--)
#define REPO(i, n) for(ll i = 1;i <= n;i++)
#define ll long long
#define INF (ll)1 << 60
#define MINF (-1 * INF)
#define ALL(n) n.begin(),n.end()
#define MOD 1000000007
#define P pair<ll, ll>

ll a, b, n, s1[110], s2[110];
set<ll>aa, bb;
int main() {
	cin >> a >> b >> n;
	REP(i, n)cin >> s1[i] >> s2[i];
	REP(i, n) {
		aa.insert(s1[i]);
		bb.insert(s2[i]);
	}
	cout << aa.size() * b + bb.size() * a - aa.size() * bb.size() - n << endl;
}