#include <bits/stdc++.h>
using namespace std;

struct Graph{
	int l, r, n, s, d;
	vector < vector <int> > graph;
	vector < vector <int> > cap;
	vector <int> pr;

	Graph(int _l, int _r): l(_l), r(_r), n(l + r + 2),
		s(0), d(n - 1), graph(n), cap(n, vector<int>(n)), pr(n) {

			for (int i = 1; i <= l; ++i)
				AddEdge(s, i);

			for (int i = l + 1; i <= l + r; ++i)
				AddEdge(i, d);
		}

	void AddEdge(int a, int b){
		graph[a].push_back(b);
		graph[b].push_back(a);
		cap[a][b] = 1;
	}

	bool bfs(){
		queue <int> Q;
		fill(pr.begin(), pr.end(), 1e9);

		Q.push(s);
		pr[s] = -1;

		while (not Q.empty()){
			int node = Q.front();
			Q.pop();

			for (int nei : graph[node]){
				if (pr[nei] == 1e9 && cap[node][nei]){
					pr[nei] = node;
					Q.push(nei);
				}
			}
		}

		return (pr[d] != 1e9);
	}

	vector < pair <int, int> > maxFlow(vector < pair <int, int> >& edges){
		int maxFlow = 0;
		while (bfs()){
			int flow = 1e9;
			for (int node = d; node != s; node = pr[node])
				flow = min(flow, cap[pr[node]][node]);

			for (int node = d; node != s; node = pr[node]){
				cap[pr[node]][node] -= flow;
				cap[node][pr[node]] += flow;
			}
			maxFlow += flow;
		}

		vector < pair <int, int> > ans;
		for (auto& it: edges){
			int a = it.first;
			int b = it.second;
			if (!cap[a][b])
				ans.emplace_back(a, b - l);
		}

		assert(maxFlow == (int) ans.size());

		return ans;
	}


};

int main(){
	ifstream cin("cuplaj.in");
	ofstream cout("cuplaj.out");

	int l, r, m;
	cin >> l >> r >> m;

	Graph G(l, r);

	vector < pair <int, int> > edges;
	while (m--){
		int a, b;
		cin >> a >> b;
		G.AddEdge(a, l + b);
		edges.emplace_back(a, b + l);
	}

	auto ans = G.maxFlow(edges);

	cout << ans.size() << '\n';
	for (auto& it: ans)
		cout << it.first << ' ' << it.second << '\n';

	return 0;
}