#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>
using namespace std;
#define ech(It, A) for (typeof(A.begin()) It = A.begin(); It != A.end(); ++It)

vector< vector<int> > adjl;
vector<int> match1;
vector<int> match2;
vector<int> visited;
int color;

bool dfs( int idx ) {
	visited[idx] = color;
	ech(it, adjl[idx]) { 
		if (match2[*it] == 0) {
			match1[idx] = *it;
			match2[*it] = idx;
			return true;
		}
	}

	ech(it, adjl[idx]) { 
		if ( visited[*it] != color && dfs(*it) ) {
			match1[idx] = *it;
			match2[*it] = idx;
			return true;
		}
	}
	return false;
}

int main() {
	ifstream fin("cuplaj.in");
	ofstream fout("cuplaj.out");
	int n, m, e;
	fin >> n >> m >> e;
	adjl.resize(n+1);
	match1.resize(n+1);
	match2.resize(m+1);
	visited.resize(m+1);

	for (int u, v, i = 0; i < e; ++i) {
		fin >> u >> v;
		adjl[u].push_back(v);
	}

	int cnt = 0;
	for (int i = 1; i <= n; ++i) {
		color = i;
		if (dfs(i)) ++cnt;
	}

	fout << cnt << '\n';
	for (int i = 1; i <= n; ++i) {
		if (match1[i] != 0)
			fout << i << ' ' << match1[i] << '\n';
	}
	return 0;
}