#include <iostream>
#include <numeric>
#include <vector>
#include <unordered_map>
using namespace std;

int main() {
	long long w, h, n;
	cin >> w >> h >> n;
	unordered_map<long long, long long> group_types, group_nums;

	for (int i = 0; i < n; i++) {
		int type, num;
		cin >> type >> num;
		group_types[type] = h;

		if (group_nums.find(num) == group_nums.end())
			group_nums[num] = 0;
		else
			group_nums[num]++;
	}

	vector<long long> count_types;
	for (auto pair : group_types)
		count_types.push_back(pair.second);

	long long sum = 0;
	long long count_same_num = w - 1;
	int start = 0;
	for (auto pair : group_nums) {
		for (int i = start; i < count_types.size(); i++) {
			count_types[i]--;
		}
		sum += count_same_num - group_nums[pair.first];
		count_same_num--;
		start++;
	}

	cout << accumulate(count_types.begin(), count_types.end(), sum) << endl;

	return 0;
}