#include <bits/stdc++.h>
using namespace std;
const int MAXN = 200005;
const int MAXM = 200005;
struct edge {int to, val, nxt;} edges[MAXM << 1]; int head[MAXN], tot = 1;
void add(int u, int v, int w) {
	edges[++tot].to = v; edges[tot].val = w; edges[tot].nxt = head[u]; head[u] = tot;
}
int key[MAXN], dep[MAXN];
bool bfs(int s, int t, int n) {
	for (int i = 1; i <= n; i++) key[i] = head[i], dep[i] = 0;
	dep[s] = 1; queue<int> q; q.push(s); while (q.empty() == 0) {
		int u = q.front(); q.pop(); for (int i = head[u]; i; i = edges[i].nxt) {
			if (edges[i].val && dep[edges[i].to] == 0) {
				dep[edges[i].to] = dep[u] + 1; q.push(edges[i].to);
			}
		}
	} return dep[t];
}
int dfs(int u, int f, int t) {
	if (f == 0 || u == t) return f; int ans = 0;
	for (int &i = key[u]; i; i = edges[i].nxt) {
		if (dep[edges[i].to] != dep[u] + 1) continue;
		int x = dfs(edges[i].to, min(f - ans, edges[i].val), t);
		edges[i].val -= x; edges[i ^ 1].val += x; ans += x;
		if (ans == f) break;
	}
	return ans;
}
int flow(int s, int t, int n) {
	int ans = 0; while (bfs(s, t, n)) ans += dfs(s, 0x7fffffff, t); return ans;
}
int main() {
	int l, r, m; scanf("%d %d %d", &l, &r, &m);
	int s = l + r + 1, t = s + 1;
	for (int i = 1; i <= m; i++) {
		int u, v; scanf("%d %d", &u, &v); u++; v++;
		add(u, v + l, 1); add(v + l, u, 0);
	}
	for (int i = 1; i <= l; i++) add(s, i, 1), add(i, s, 0);
	for (int i = 1; i <= r; i++) add(i + l, t, 1), add(t, i + l, 0);
	printf("%d\n", flow(s, t, t));
	for (int i = 1; i <= l; i++) {
		for (int j = head[i]; j; j = edges[j].nxt) {
			if (edges[j].to > l && edges[j].to <= l + r && edges[j].val == 0) {
				printf("%d %d\n", i - 1, edges[j].to - l - 1);
			}
		}
	}
}