#include<bits/stdc++.h>
using namespace std;
  #define int long long
#define F(i, l, r) for(int i = (l); i <= (r); ++i)
#define dF(i, r, l) for(int i = (r); i >= (l); --i)

int ri() {
	int x = 0, f = 1;
	char c = getchar();
	while(c < '0' || c > '9') {
		if(c == '-') f = -1;
		c = getchar();
	}
	while(c >= '0' && c <= '9') {
		x = x* 10 + c - 48;
		c  = getchar();
	} return x * f;
}

const int _ = 3e5 + 5;

int n, m;

struct MCMF {
	int s, t, tot = 1, head[_], to[_ << 1], nxt[_ << 1], cur[_], fl[_ << 1];
	int dis[_];
	void add(int u, int v, int w) {
		to[++tot] = v, nxt[tot] = head[u], head[u] = tot, fl[tot] = w;
	}
	void Add(int u, int v, int w) {
		add(u, v, w), add(v, u, 0);
	}
	bool bfs() {
		F(i, 0, n + 2) dis[i] = -1;
		dis[s] = 0;
		queue<int > q;
		q.push(s);
		memcpy(cur, head, sizeof (cur));
		while(!q.empty()) {
			int u = q.front();
			q.pop();
			for(int i = head[u], v = to[i]; i; i = nxt[i], v = to[i]) {
				if(fl[i] > 0 && dis[v] == -1) {
					dis[v] = dis[u] + 1;
					q.push(v);
				}
			}
		}
		return dis[t] != -1;
	}
	bool lv[_];
	int dfs(int u, int flow = 0x3f3f3f3f) {
		if(u == t) return flow;
		int rmn = flow;
		lv[u] = 1;
		for(int &i = cur[u], v = to[i]; i && rmn; i = nxt[i], v = to[i]) {
			if(fl[i] > 0 && !lv[v] &&dis[v] == dis[u] + 1) {
				int c = dfs(v, min(rmn, fl[i]));
				fl[i] -= c, fl[i ^ 1] += c;
				rmn -= c;
			}
		}
		lv[u] = 0;
		return flow - rmn;
	}
	int dinic() {
		int res = 0;
		while(bfs()) {
			res += dfs(s);
		} return res;
	}
} S;

int Id[_];
pair<int, int> p[_];

signed main() {
	int L = ri(), R = ri();
	m = ri();
	n = L + R + 5;
	S.s = L + R + 1, S.t = S.s + 1;
	F(i, 1, L) S.Add(S.s, i, 1);
	F(i, 1, R) S.Add(i + L, S.t, 1);
	F(i, 1, m) {
		int u = ri() + 1, v = ri() + 1;
		p[i] = {u, v};
		Id[i] = S.tot + 1;
		S.Add(u, v + L, 1);
	}
	cout << S.dinic() <<'\n';
	F(i, 1, m) if(S.fl[Id[i]] == 0) {
		cout << p[i].first - 1<< ' ' << p[i].second - 1<<'\n';
	}
}