#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <cassert>
#include <vector>
#include <set>
#include <unordered_set>
#include <unordered_map>
typedef long long ll;
typedef std::vector<int> Vint;
typedef std::vector<ll> Vll;
typedef std::set<int> Sint;
typedef std::unordered_set<int> USint;
const int LEN = 1e5 + 10;

#define ADD 1
#define DEL -1

//#define MAP

int N, w, h, xi, yi;
int P[LEN];//disjoint set
int find(int i) { return P[i] < 0 ? i : P[i] = find(P[i]); }
bool join(int i, int j) {
	i = find(i), j = find(j);
	if (i == j) return 0;
	if (P[i] < P[j]) P[i] += P[j], P[j] = i;
	else P[j] += P[i], P[i] = j;
	return 1;
}
int idx_bi_search(const Vint& A, const int& x) {
	int s = 0, e = A.size() - 1, m;
	while (s <= e) {
		m = s + e >> 1;
		if (A[m] == x) return m;
		else if (A[m] > x) e = m - 1;
		else s = m + 1;
	}
	return -1;
}
struct H_event {
	int l, r, y, i;
	H_event(int l_ = 0, int r_ = 0, int y_ = 0, int i_ = 0) : l(l_), r(r_), y(y_), i(i_) {}
	bool operator < (const H_event& h) const { return y == h.y ? l < h.l : y < h.y; }
} H[LEN]; int hp;
struct V_event {
	int x, y, ev, i;
	V_event(int x_ = 0, int y_ = 0, int ev_ = 0, int i_ = 0) : x(x_), y(y_), ev(ev_), i(i_) {}
	bool operator < (const V_event& v) const { return y == v.y ? x < v.x : y < v.y; }
} V[LEN << 1]; int vp;
int hi_y[LEN];//highest y coord' of vertical event
//USint inxs[LEN << 4];//seg_tree
Sint inxs[LEN << 4];//seg_tree
int seg_v[LEN << 4];//seg_tree
int seg_p[LEN << 4];//seg_tree
void update_vertical(const int& x, const int& ev, const int& idx, int s = 0, int e = xi - 1, int i = 1) {
	if (x < s || e < x) return;
	if (ev == ADD) inxs[i].insert(idx);
	else if (ev == DEL) {
		inxs[i].erase(idx);
		if (seg_v[i] == idx) seg_v[i] = -1;//erase all vertical
	}
	if (s == e) { seg_p[i] += ev; return; }
	int m = s + e >> 1;
	update_vertical(x, ev, idx, s, m, i << 1);
	update_vertical(x, ev, idx, m + 1, e, i << 1 | 1);
	seg_p[i] = seg_p[i << 1] + seg_p[i << 1 | 1];
	return;
}
int sum_horizontal(const int& l, const int& r, const int& idx, int s = 0, int e = xi - 1, int i = 1) {
	if (r < s || e < l) return 0;
	if (l <= s && e <= r) {
		if (seg_v[i] != -1) join(idx, seg_v[i]);//find new intersection
		for (const int& v : inxs[i]) {
			join(idx, v);
			if (seg_v[i] == -1 || hi_y[v] > hi_y[seg_v[i]]) seg_v[i] = v;//highest y coord'
		}
		inxs[i].clear();
		return seg_p[i];
	}
	int m = s + e >> 1;
	return sum_horizontal(l, r, idx, s, m, i << 1) + sum_horizontal(l, r, idx, m + 1, e, i << 1 | 1);
}
void solve() {
	std::cin.tie(0)->sync_with_stdio(0);
	std::cout.tie(0);
	std::cin >> h >> w >> N;
	Vint X = { 0, w };
	Vint Y = { 0, h, h + 1 };
	hp = 0; vp = 0;
	for (int i = 0, a, b, c, d; i < N; i++) {
		std::cin >> a >> b >> c >> d;
		if (a != c) {
			H[hp++] = H_event(a, c, b, i);
		}
		else if (b != d) {
			hi_y[i] = d;
			d++;
			V[vp++] = V_event(a, b, ADD, i);
			V[vp++] = V_event(a, d, DEL, i);
		}
		X.push_back(a); X.push_back(c);
		Y.push_back(b); Y.push_back(d);
	}
	H[hp++] = H_event(0, w, 0, N);
	H[hp++] = H_event(0, w, h, N);
	V[vp++] = V_event(0, 0, ADD, N);
	V[vp++] = V_event(w, 0, ADD, N);
	V[vp++] = V_event(0, h + 1, DEL, N);
	V[vp++] = V_event(w, h + 1, DEL, N);

	std::sort(X.begin(), X.end()); X.erase(unique(X.begin(), X.end()), X.end());
	std::sort(Y.begin(), Y.end()); Y.erase(unique(Y.begin(), Y.end()), Y.end());
	std::sort(H, H + hp);
	std::sort(V, V + vp);
	memset(P, -1, sizeof P);
	memset(seg_v, -1, sizeof seg_v);
	memset(seg_p, 0, sizeof seg_p);

	xi = X.size();
	yi = Y.size();

#ifdef MAP
	std::unordered_map<int, int> mx;
	for (int i = 0; i < xi; i++) mx[X[i]] = i;
#endif

	ll e = 0, v = 0, chi = 0;
	for (int y = 0, i = 0, j = 0; y < yi; y++) {
		//while (i < vp && idx_bi_search(Y, V[i].y) == y) {//vertical events
		while (i < vp && V[i].y == Y[y]) {//vertical events
			v++;
			e += V[i].ev == DEL;
			update_vertical(idx_bi_search(X, V[i].x), V[i].ev, V[i].i);
			i++;
		}
		//while (j < hp && idx_bi_search(Y, H[j].y) == y) {//horizontal events
		while (j < hp && H[j].y == Y[y]) {//horizontal events
#ifdef MAP
			int l_ = mx[H[j].l];
			int r_ = mx[H[j].r];
#else
			int l_ = idx_bi_search(X, H[j].l);
			int r_ = idx_bi_search(X, H[j].r);
#endif
			int cnt = sum_horizontal(l_, r_, H[j].i);
			e += cnt * 2 + 1;
			v += cnt + 2;
			j++;
		}
	}
	for (int i = 0; i <= N; i++) if (i == find(i)) chi++;
	std::cout << chi - v + e << "\n";//X = v - e + f
	return;
}
int main() { solve(); return 0; }//boj10049 cutting  refer to Jay0202