#include <iostream>
#include <memory.h>
using namespace std;
#define REP(i,N)	for(int i=0;i<(N);++i)
#define FOR(i,a,b)	for(int i=(a);i<=(b);++i)
#define FORD(i,a,b)	for(int i=(a);i>=(b);--i)

#define MAXNODES 1005

bool adjacent[MAXNODES][MAXNODES];
//Structures required for finding the maximum matching
int matching[2][MAXNODES];
int path[2*MAXNODES];
bool visited[2][MAXNODES];
int L;        //Length of the augmenting path found
int N, K;    //Number of nodes on side 0 and 1 respectively

bool find_augmenting_path(int node, int side)
{
	visited[side][node] = true;
	path[L++] = node;

	if(side == 0) {
		FOR(i,1,K) {
			if(!visited[1][i] && adjacent[node][i] && matching[0][node]!=i) 
				if(find_augmenting_path(i,1)) return true;
		}
	} else {
		if(matching[1][node] == 0)
			return true;
		else {
			if(!visited[0][matching[1][node]])
				if(find_augmenting_path(matching[1][node],0)) return true;
		}
	}

	--L;
	return false;
}

int main()
{
	int C, c, e;
	scanf("%d %d %d", &N, &K, &C);
	while(C--) {
		scanf("%d %d", &c, &e);
		adjacent[c][e] = true;
	}

	//Try finding an augmenting path till none can be found
	while(1) {
		bool more_augmenting_path = false;
		memset(visited,0,sizeof(visited));    //Set all nodes as NOT visited
		L = 0;
		FOR(i,1,N) {
			if(matching[0][i] == 0) {    //Find first unmatched node
				if(find_augmenting_path(i,0)) {
					more_augmenting_path = true;
					break;
				}
			}
		}
		if(more_augmenting_path) {
			for(int i = 0 ; i < L ; i+=2) {
				matching[0][path[i]] = path[i+1];
				matching[1][path[i+1]] = path[i];
			}
		} else {
			break;
		}
	}

	int count = 0;
	FOR(i,1,N) if(matching[0][i] != 0) ++count;
	printf("%d\n", count);
	FOR(i,1,N) if(matching[0][i] != 0) printf("%d %d\n", i, matching[0][i]);

	return 0;
}