#include <iostream>
#include <cstdio>
#include <vector>
#include <bitset>
#include <utility>
#include <algorithm>

#define NMAX 10005
#define pb push_back

using namespace std;

vector<int> G[NMAX];
int L[NMAX], R[NMAX];
bitset<NMAX> U;
int n, m, e;

bool pairup(int nod)
{
	if (U[nod]) return 0;
	U[nod] = 1;

	for (vector<int> ::iterator it = G[nod].begin(); it != G[nod].end(); ++it)
		if (!R[*it])
		{
			L[nod] = *it;
			R[*it] = nod;
			return 1;
		}
	for (vector<int> ::iterator it = G[nod].begin(); it != G[nod].end(); ++it)
		if (pairup(R[*it]))
		{
			L[nod] = *it;
			R[*it] = nod;
			return 1;
		}
	return 0;
}
int main()
{
	freopen("cuplaj.in", "rt", stdin);
	freopen("cuplaj.out", "w", stdout);

	int x, y;

	cin >> n >> m >> e;
	while (e--)
	{
		cin >> x >> y;
		G[x].push_back(y);
	}

	for (bool change = 1; change;)
	{
		change = 0;
		U.reset();
		for (int i = 1; i <= n; ++i)
			if (!L[i]) change |= pairup(i);
	}

	int dimCuplaj = 0;
	for (int i = 1; i <= n; ++i)
		dimCuplaj += (L[i] > 0);
	cout << dimCuplaj << '\n';

	for (int i = 1; i <= n; ++i)
		if (L[i]) cout << i << ' ' << L[i] << '\n';
	return 0;
}