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

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

const int NMAX = 10005;

bitset <NMAX> used;

vector <int> g[NMAX];

int r[NMAX], l[NMAX], n, m, e, x, y;

bool pair_up(int node)
{
	if (used[node])
		return 0;

	used[node] = 1;
	
	for (size_t i = 0; i < g[node].size(); ++i)
	{
		int y = g[node][i];
		if (!l[y] || pair_up(l[y]))
		{
			l[y] = node;
			r[node] = y;
			return 1;
		}
	}
	return 0;
}

int main()
{
	fin >> n >> m >> e;
	for (int i = 1; i <= e; ++i)
	{
		fin >> x >> y;
		g[x].push_back(y);
	}
	int cnt = 0;
	for (bool ok = true; ok; ) 
	{
		ok = 0;
		used.reset();
		for (int i = 1; i <= n; ++i)
			if (!r[i] && pair_up(i))
			{
				++cnt;
				ok = 1;
			}
	}

	fout << cnt << "\n";
	for (int i = 1; i <= n; ++i)
		if (r[i])
			fout << i << " " << r[i] << "\n";

	fout.close();
	return 0;
}