#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int S = 1, T = 2;
#define PC (ln + rn + 2)
int ln, rn, m;
int L(int x) { return x + 2; }
int R(int x) { return x + ln + 2; }
struct Edge {
	int v, nxt;
	ll w;
} e[1000005];
int head[200005], len = 1;
void Insert(int u, int v, ll w) {
	e[++len] = { v, head[u], w };
	head[u] = len;
}
void InsertF(int u, int v, ll w) { Insert(u, v, w), Insert(v, u, 0); }
int cur[200005], dis[200005], gap[200005];
ll DFS(int u, ll rest) {
	if (u == T) return rest;
	ll res = 0;
	for (int &i = cur[u]; i; i = e[i].nxt) {
		int v = e[i].v;
		if (dis[u] != dis[v] + 1 || !e[i].w) continue;
		ll x = DFS(v, min(rest, e[i].w));
		e[i].w -= x, e[i ^ 1].w += x;
		rest -= x, res += x;
		if (!rest) return res;
	}
	cur[u] = head[u];
	if (!--gap[dis[u]]) dis[S] = PC;
	gap[++dis[u]]++;
	return res;
}
ll Dinic() {
	ll res = 0;
	while (dis[S] < PC) res += DFS(S, 1e18);
	return res;
}
int main() {
	scanf("%d%d%d", &ln, &rn, &m);
	for (int i = 1; i <= m; i++) {
		int a, b; scanf("%d%d", &a, &b);
		InsertF(L(a + 1), R(b + 1), 1);
	}
	for (int i = 1; i <= ln; i++) InsertF(S, L(i), 1);
	for (int i = 1; i <= rn; i++) InsertF(R(i), T, 1);
	printf("%lld\n", Dinic());
	for (int i = 2; i <= m * 2; i += 2) {
		if (!e[i].w) {
			int u = e[i ^ 1].v, v = e[i].v;
			printf("%d %d\n", u - 3, v - 3 - ln);
		}
	}
	return 0;
}