#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <queue>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <fstream>
using namespace std;

const string file = "cuplaj";

const string infile = file + ".in";
const string outfile = file + ".out";

const int INF = 0x3f3f3f3f;


vector<vector<int> > G;
vector<int> Match;
vector<bool> uz;
int N, M, L;


bool canPair(int i)
{
	if(uz[i])
		return false;
	uz[i] = true;

	for(vector<int>::iterator itr = G[i].begin();
		itr != G[i].end();
		itr++)
	{
		if(Match[*itr] == 0 || canPair(Match[*itr]))
		{
			Match[*itr] = i;
			return true;
		}
	}
	return false;
}


int main()
{
	fstream fin(infile.c_str(), ios::in);
	fin >> N >> M >> L;
	G.resize(N + 1);
	Match.resize(M + 1);
	for(int i = 0; i < L; i++)
	{
		int x, y;
		fin >> x >> y;
		G[x].push_back(y);
	}
	fin.close();

	
	
	bool improv = true;
	int MaxMatch = 0;
	while(improv)
	{
		improv = false;
		uz.clear();
		uz.resize(M + 1);
		for(int i = 1; i <= N; i++)
		{
			if(canPair(i))
			{
				improv = true;
				MaxMatch ++;
			}
		}
	}


	fstream fout(outfile.c_str(), ios::out);
	fout << MaxMatch << "\n";
	for(int i = 1; i <= M; i++)
	{
		if(Match[i] != 0)
		{
			fout << Match[i] << " " << i << "\n";
		}
	}
	fout.close();
}