#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";

bool canPair(int i, vector<bool>& uz, vector<vector<int> >& G, vector<int>& match)
{
	if(uz[i] == true)
		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], uz, G, match))
		{
			match[i] = *itr;
			match[*itr] = i;
			return true;
		}
	}
	return false;
}

int main()
{

	int N, M, E;
	vector<vector<int> > G;
	vector<int> match;

	int totalMatch = 0;

	fstream fin(infile.c_str(), ios::in);

	fin >> N >> M >> E;

	G.resize(N + M + 1);
	match.resize( N + M + 1);

	for(int i = 0; i < E; i++)
	{
		int x, y;
		fin >> x >> y;

		G[x].push_back(y + N);
	}

	fin.close();


	bool improve = true;
	while(improve)
	{
		improve = false;
		vector<bool> uz(N + 1);
		for(int i = 1; i <= N; i++)
		{
			if(match[i] == 0)
			{
				if(canPair(i, uz, G, match))
				{
					totalMatch ++;
					improve = true;
				}
			}
		}
	}

	
	fstream fout(outfile.c_str(), ios::out);
	fout << totalMatch << "\n";
	for(int i = 1; i <= N; i++)
	{
		if(match[i] != 0)
		{
			fout << i << " " << match[i] - N << "\n";
		}
	}

	fout.close();
}