#include <stdio.h>
#include <vector>
#define MAX 10005
#define INF 1<<30
#define pb push_back
using namespace std;

vector<int> l[MAX];
vector<int> q;
int n, m, e, x, y, i, pair1[MAX], pair2[MAX], dist[MAX];

bool BFS();
bool DFS(int x);
int HK();

int main(){
	freopen("cuplaj.in", "r", stdin);
	freopen("cuplaj.out", "w", stdout);
	scanf("%d%d%d", &n, &m, &e);
	for(i = 0; i < e; i++){
		scanf("%d%d", &x, &y);
		l[x].pb(y);
	}

	printf("%d\n", HK());
	for(i = 1; i <= n; i++)
		if(pair1[i])
			printf("%d %d\n", i, pair1[i]);
	return 0;
}

bool BFS(){
	for(i = 1; i <= n; i++){
		if(!pair1[i]){
			dist[i] = 0;
			q.pb(i);
		}

		else
			dist[i] = INF;
	}
	dist[0] = INF;

	while(!q.empty()){
		i = q.front();
		q.erase(q.begin());
		if(dist[i] < dist[0]){
			vector<int>::iterator it = l[i].begin();
			for(it; it < l[i].end(); it++)
				if(dist[pair2[*it]] == INF){
					dist[pair2[*it]] = dist[i] + 1;
					q.pb(pair2[*it]);
				}
		}
	}
	return dist[0] != INF;
}

bool DFS(int x){
	if(x != 0){
		vector<int>::iterator it = l[x].begin();
		for(it; it < l[x].end(); it++)
			if(dist[pair2[*it]] == dist[x] + 1 && DFS(pair2[*it])){
					pair2[*it] = x;
					pair1[x] = *it;
					return true;
			}

		dist[x] = INF;
		return false;
	}
	return true;
}

int HK(){
	int nr = 0;
	while(BFS()){
		for(i = 1; i <= n; i++)
			if(!pair1[i] && DFS(i))
					nr++;
	}
	return nr;
}