#include <cstdio>
#include <cstring>
#include <vector>
using namespace std;

const int N_MAX = 100001;

int n,m,e, rez;
bool view[N_MAX];
int cuplaj[N_MAX];
bool cupla[N_MAX];
vector<int> G[N_MAX];

int pair_up ( int nod ) {
	if (view[nod])
		return 0;
	view[nod] = true;
	for (vector<int>::iterator it = G[nod].begin(); it != G[nod].end(); ++it) {
		if (!cuplaj[*it]) {
			cuplaj[*it] = nod;
			return 1;
		}
	}
	for (vector<int>::iterator it = G[nod].begin(); it != G[nod].end(); ++it) {
		if (cuplaj[*it] && cuplaj[*it] != nod && pair_up(cuplaj[*it])) {
			cuplaj[*it] = nod;
			return 1;
		}
	}
	return 0;
}

int main() {
	freopen("cuplaj.in","rt",stdin);
	freopen("cuplaj.out","wt",stdout);
	scanf("%d %d %d",&n,&m,&e);
	for (int i = 0, a,b; i < e; ++i) {
		scanf("%d %d",&a,&b);
		G[a].push_back(b);
	}
	bool ok = true;
	while (ok) {
		memset(view,0,sizeof(view));
		ok = false;
		for (int i = 1; i <= n; ++i) {
			if (!cupla[i] && pair_up(i)) {
				cupla[i] = true;
				++rez;
				ok = true;
			}
		}
	}
	printf("%d\n",rez);
	for (int i = 1; i <= m; ++i)
		if (cuplaj[i])
			printf("%d %d\n",cuplaj[i],i);
	return 0;
}