#include <fstream>
#include <iostream>
#include <vector>
#include <cstring>
#include <queue>

using namespace std;

const int NMAX = 10003;
vector<int> G[NMAX];
int n, m;
int st[NMAX], dr[NMAX];
bool viz[NMAX];

void read_data() 
{
	ifstream fin("cuplaj.in");
	int e;
	fin >> n >> m >> e;
	for (int i = 0; i < e; ++i) {
		int x, y;
		fin >> x >> y;
		G[x].push_back(y);
	}
}

bool pairup(const int x) 
{
	if (viz[x])
		return false;
	viz[x] = true;
	
	vector<int>::iterator it;
	for (it = G[x].begin(); it!=G[x].end(); ++it) 
		if (!dr[*it]){
			dr[*it] = x;
			st[x] = *it;
			return true;
		}
	for (it = G[x].begin(); it!=G[x].end(); ++it) 
		if (pairup(dr[*it])){
			st[x] = *it;
			dr[*it] = x;
			return true;
		}
	return false;
}

void cuplaj()
{
	bool changed = true;
	while (changed) {
		changed = false;
		memset(viz, 0, sizeof(viz));
		for (int i = 1; i <= n; ++i)
			if (!st[i])
				changed |= pairup(i);
	}
}

int main()
{
	read_data();
	cuplaj();
	
	int cuplaj = 0;
	for (int i = 1; i <= n; ++i)
		cuplaj += st[i] > 0;
	
	ofstream fout("cuplaj.out");
	fout << cuplaj << endl;
	for (int i = 1; i <= n; ++i)
		if (st[i])
			fout << i << " " << st[i] << "\n";
	return 0; 
}