#include <fstream>
#include <algorithm>
#include <bitset>
#include <vector>
#include <array>
#include <cstring>
using namespace std;

constexpr int maxn = 10010;

array<vector<int>, maxn> graf;
array<int, maxn> st = {}, dr = {}, tried = {};

static bool try_to_repair(const int x){
	if(tried[x]){
		return false; }
	tried[x] = true;
	for(const auto y : graf[x]){
		if(st[y] == -1){
			dr[x] = y;
			st[y] = x;
			return true; } }
	for(const auto y : graf[x]){
		if(try_to_repair(st[y])){
			dr[x] = y;
			st[y] = x;
			return true; } }
	return false; }

int main(){
	ifstream f("cuplaj.in");
	ofstream g("cuplaj.out");
	int n, m, e;

	f >> n >> m >> e;

	for(int i = 0, a, b; i < e; ++i){
		f >> a >> b;
		graf[a-1].push_back(b-1); }
	fill(begin(st), end(st), -1);
	fill(begin(dr), end(dr), -1);

	for(bool changed = true; changed; ){
		changed = false;
		memset(&tried[0], 0, sizeof(int) * n);
		for(int i = 0; i < n; ++i){
			if(dr[i] == -1){
				changed = changed || try_to_repair(i); } } }

	const int sz_cuplaj = count_if(begin(dr), begin(dr)+n, [](const int x){ return x != -1; });
	g << sz_cuplaj << endl;
	for(int i = 0; i < n; ++i){
		if(dr[i] != -1){
			g << i+1 << ' ' << dr[i]+1 << endl; } }

	return 0; }