// Skyqwq
#include <bits/stdc++.h>

#define fi first
#define se second
#define mp make_pair
#define pb push_back

using namespace std;

typedef pair<int, int> PII;
typedef long long LL;

template <typename T> bool inline chkMin(T &x, T y) { return (y < x) ? x = y, 1 : 0; }
template <typename T> bool inline chkMax(T &x, T y) { return (y > x) ? x = y, 1 : 0; }

template <typename T> void inline read(T &x) {
	x = 0; int f = 1; char s = getchar();
	while (s > '9' || s < '0') { if (s == '-') f = -1; s = getchar(); }
	while (s <= '9' && s >= '0') x = x * 10 + s - '0', s = getchar();
	x *= f;
}

const int N = 2e5 + 5, M = 2e5 + 5;

const LL INF = 1e18;

int n, m, s, t, v, A[M], B[M], C[M];

struct E{
	int next, v, w;
} e[M << 1];

int head[N], numE = 1;

void add(int u, int v, int w) {
	e[++numE] = (E) { head[u], v, w };
	head[u] = numE;
}

void addE(int u, int v, int w) {
	add(u, v, w), add(v, u, 0);
}

int q[N], d[N], cur[N];

bool bfs() {
	memset(d, 0x3f, sizeof d);
	d[s] = 0;
	int hh = 0, tt = 0;
	q[0] = s; cur[s] = head[s];
	while (hh <= tt) {
		int u = q[hh++];
		for (int i = head[u]; i; i = e[i].next) {
			int v = e[i].v;
			if (e[i].w && d[u] + 1 < d[v]) {
				d[v] = d[u] + 1;
				q[++tt] = v; cur[v] = head[v];
				if (v == t) return 1;
			}
		}
	}
	return 0;
}

LL dinic(int u, LL flow) {
	if (u == t) return flow;
	LL rest = flow;
	for (int i = head[u]; i && rest; i = e[i].next) {
		int v = e[i].v;
		if (e[i].w && d[u] + 1 == d[v]) {
			LL k = dinic(v, min((LL)e[i].w, rest));
			if (!k) d[v] = 0;
			else {
				e[i].w -= k, e[i ^ 1].w += k, rest -= k;
			}
		}
	}
	return flow - rest;
}

int main() {
	int L, R, m; read(L), read(R), read(m);
	n = L + R + 2;
	s = n - 1, t = n;
//	read(n), read(m); read(s), read(t);	
	for (int i = 1; i <= m; i++) {
		int u, v; read(u), read(v);
		++u, ++v;
		addE(u, v + L, 1);
		A[i] = u, B[i] = v, C[i] = numE;
	}
	for (int i = 1; i <= L; i++) addE(s, i, 1);
	for (int i = 1; i <= R; i++) addE(i + L, t, 1);
	LL ans = 0, ret = 0;
	while (bfs()) {
		while (ret = dinic(s, INF)) ans += ret;
	}
	printf("%lld\n", ans);
	for (int i = 1; i <= m; i++) {
		if (e[C[i]].w) printf("%d %d\n", A[i] - 1, B[i] - 1);
	}
	return 0;
}