#include <bits/stdc++.h>
using namespace std;
int S, T;
struct MaxFlow {
	static constexpr int N = 2e5 + 55;
	struct edge_t {
		int v, f;
	};
	vector<edge_t> l;
	vector<int> e[N];
	void add(int u, int v, int f) {
		e[u].push_back(l.size());
		l.push_back({v, f});
		e[v].push_back(l.size());
		l.push_back({u, 0});
	}
	int dis[N], cur[N];
	bool bfs() {
		memset(dis, -1, sizeof(dis));
		queue<int> Q;
		Q.push(S);
		dis[S] = 0;
		while (!Q.empty()) {
			int u = Q.front();
			Q.pop();
			for (int i : e[u]) {
				auto [v, f] = l[i];
				if (f && dis[v] == -1) {
					dis[v] = dis[u] + 1;
					Q.push(v);
				}
			}
		}
		return dis[T] != -1;
	}
	int dfs(int u, int limit) {
		if (u == T) return limit;
		int fl = 0;
		for (int t = cur[u]; t < e[u].size() && fl < limit; t = max(t + 1, cur[u])) {
			cur[u] = t + 1;
			int i = e[u][t];
			auto &[v, f] = l[i];
			if (f && dis[v] == dis[u] + 1) {
				int g = dfs(v, min(limit - fl, f));
				fl += g;
				f -= g;
				l[i ^ 1].f += g;
				if (!f) dis[v] = -1;
			}
		}
		return fl;
	}
	int flow() {
		int res = 0;
		while (bfs()) {
			memset(cur, 0, sizeof cur);
			res += dfs(S, 1e9);
		}
		return res;
	}
} G;
int main() {
	cin.tie(0)->sync_with_stdio(0);
	int L, R, M;
	cin >> L >> R >> M;
	S = L + R + 1, T = S + 1;
	for (int i = 1, u, v; i <= M; i++) {
		cin >> u >> v;
		u++, v++;
		G.add(u, L + v, 1);
	}
	for (int i = 1; i <= L; i++) {
		G.add(S, i, 1);
	}
	for (int i = 1; i <= R; i++) {
		G.add(L + i, T, 1);
	}
	cout << G.flow() << "\n";
	for (int u = 1; u <= L; u++) {
		for (auto i : G.e[u]) {
			auto [v, f] = G.l[i];
			if (v > L && v <= L + R && !f) {
				cout << u - 1 << " " << v - L - 1 << "\n";
			}
		}
	}
	return 0;
}