#include<fstream>
#include<vector>
#include<queue>
using namespace std;

int l[10010], r[10100],dist[10100];

vector<int> G[20100],elem;
queue<int> q;

#define INFINITY (1<<30)

ifstream in("cuplaj.in");
ofstream out("cuplaj.out");

int N, M, E;

int bfs()
{
	
	for (int i = 1;i <= N;++i)
		if (!l[i])
		{
			dist[i] = 0;
			q.push(i);
		}
		else
			dist[i] = INFINITY;

	dist[0] = INFINITY;

	while (q.size())
	{
		int node = q.front();
		if(dist[node]<dist[0])
			for (int i = 0;i < G[node].size();++i)
				if (dist[r[G[node][i]]] == INFINITY)
				{
					dist[r[G[node][i]]] = dist[node] + 1;
					q.push(r[G[node][i]]);
				}
		q.pop();
	}
	return dist[0] != INFINITY;
}

int dfs(int x)
{
	if (x)
	{
		for (int i = 0;i < G[x].size();++i)
			if (dist[r[G[x][i]]] == dist[x] + 1)
			{
				if (dfs(r[G[x][i]]))
				{
					r[G[x][i]] = x;
					l[x] = G[x][i];
					return 1;
				}
			}
		return 0;
	}
	else
		return 1;
}


int main()
{
	

	in >> N >> M >> E;

	for (int i = 1;i <= E;++i)
	{
		int x, y;
		in >> x >> y;
		G[x].push_back(y);
	}

	int change = 1;

	int maximum_matching = 0;

	while (bfs())
	{
		for (int i = 1;i <= N;++i)
		{
			if (l[i] == 0 && dfs(i))
			{
				++maximum_matching;
			}
		}
	}

	out << maximum_matching << '\n';

	for (int i = 1;i <= N;++i)
		if (l[i] > 0)
			out << i << " " << l[i] << '\n';

	return 0;
}