#include <iostream>
#include <fstream>
#include <vector>
#include <bitset>


typedef std::vector<int>::iterator iter;


const int MAXN = 10005;
std::ifstream f("cuplaj.in");
std::ofstream g("cuplaj.out");
std::vector<int> G[MAXN]; int n, m, e;
std::bitset<MAXN> viz;
int left[MAXN], right[MAXN];


bool match(int node)
{
	if (viz[node] == true) {
		return false;
	}
	viz[node] = true;

	for (iter it = G[node].begin(); it != G[node].end(); it++) {
		if (right[*it] == 0) {
			right[*it] = node;
			left[node] = *it;
			return true;
		}
	}
	for (iter it = G[node].begin(); it != G[node].end(); it++) {
		if (match(right[*it]) == true) {
			right[*it] = node;
			left[node] = *it;
			return true;
		}
	}
	return false;
}


int main()
{
	f >> n >> m >> e;
	for (int i = 1, x, y; i <= e; i++) {
		f >> x >> y;
		G[x].push_back(y);
	}


	bool ok = true;
	while (ok)
	{
		ok = false;
		viz.reset();
		for (int i = 1; i <= n; i++) {
			if (left[i] == 0) {
				ok |= match(i);
			}
		}
	}

	int sol = 0;
	for (int i = 1; i <= n; i++) {
		if (left[i] != 0) {
			sol++;
		}
	}
	g << sol << std::endl;
	for (int i = 1; i <= n; i++) {
		if (left[i] != 0) {
			g << i << ' ' << left[i] << '\n';
		}
	}
	g.flush();


	//system("pause");
	f.close();
	g.close();
	return 0;
}