#include <bits/stdc++.h>
using namespace std;
ifstream f("cuplaj.in");
ofstream g("cuplaj.out");
#define cin f
#define cout g
const int Max = 20003;

int N, M, E;
int n;
unordered_map<int, int> capacity[Max];
vector<int> adj[Max];

int bfs(int s, int t, vector<int> &parent)
{
	fill(parent.begin(), parent.end(), -1);
	parent[s] = -2;

	queue<pair<int, int>> Q;
	Q.push({s, INT_MAX});

	while(! Q.empty())
	{
		int cur = Q.front().first;
		int flow = Q.front().second;
		Q.pop();

		for(int next : adj[cur])
		{
			if(parent[next] == -1 and capacity[cur][next] != 0)
			{
				parent[next] = cur;
				int new_flow = min(flow, capacity[cur][next]);

				if(next == t)
					return new_flow;

				Q.push({next, new_flow});
			}
		}
	}

	return 0;
}

int maxflow(int s, int t)
{
	int flow = 0, new_flow;
	vector<int> parent(n + 1);

	while(new_flow = bfs(s, t, parent))
	{
		flow += new_flow;

		int cur = t;
		while(cur != s)
		{
			int prev = parent[cur];
			capacity[cur][prev] += new_flow;
			capacity[prev][cur] -= new_flow;
			cur = prev;
		}
	}

	return flow;
}

int main()
{
	int s, t;
	cin >> N >> M >> E;
	n = N + M + 2;
	s = n - 1, t = n;
	for(int i = 1; i <= E; i++)
	{
		int x, y;
		cin >> x >> y;
		adj[x].push_back(y + N);
		adj[y + N].push_back(x);
		capacity[x][y + N] = 1;
		capacity[y + N][x] = 0;
	}

	for(int i = 1; i <= N; i++)
	{

		adj[s].push_back(i);
		adj[i].push_back(s);
		capacity[s][i] = 1;
		capacity[i][s] = 0;
	}

	for(int i = 1; i <= M; i ++)
	{
		adj[i + N].push_back(t);
		adj[t].push_back(i + N);
		capacity[i + N][t] = 1;
		capacity[t][i + N] = 0;
	}

	cout<<maxflow(s, t)<<'\n';

	for(int i = 1; i <= N; i ++)
		for(auto it : adj[i])
			if(it != s and capacity[i][it] == 0)
			{
				cout<<i<<' '<<it - N<<'\n';
				break;
			}

	return 0;
}