/*
灏忓簾鐗╋紝杩欓兘涓嶄細 /cf
*/
#include <bits/stdc++.h>
using namespace std;
#define ll int
#define mp make_pair
#define inf (ll)1e9
#define pii pair <ll, ll>
#define fr first
#define se second
const ll mod = 1e9 + 7;
char buf[1 << 21], *p1 = buf, *p2 = buf;
#define getchar() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, 1 << 18, stdin), p1 == p2) ? EOF : *p1++)
inline ll read() {
	ll x = 0, f = 1;
	char ch = getchar();
	while(ch < '0' || ch > '9') f = ((ch == '-') ? -1 : f), ch = getchar();
	while(ch >= '0' && ch <= '9') x = x * 10 + ch - '0', ch = getchar();
	return x * f;
}
inline void write(ll x) {
	if(x < 0) x = -x, putchar('-');
	if(x >= 10) write(x / 10);
	putchar(x % 10 + '0');
}
struct Flow {
	ll s, t, N;
	ll tot = 1;
	struct Edge {
		ll v, e, nxt;
	}edge[1000005];
	ll head[200005], cur[200005], dis[200005];
	inline void addedge(ll u, ll v, ll e) {
		edge[++tot].v = v, edge[tot].e = e, edge[tot].nxt = head[u], head[u] = tot;
	}
	inline void Addedge(ll u, ll v, ll e) {
		addedge(u, v, e);
		addedge(v, u, 0);
	} 
	inline bool bfs() {
		for(ll i = 0; i <= N; i++) dis[i] = inf, cur[i] = head[i];
		dis[s] = 0;
		queue <ll> Q;
		Q.push(s);
		while(!Q.empty()) {
			ll x = Q.front();
			Q.pop();
			for(ll i = head[x]; i; i = edge[i].nxt) {
				ll v = edge[i].v, e = edge[i].e;
				if(dis[v] > dis[x] + 1 && e) {
					dis[v] = dis[x] + 1;
					Q.push(v);
				}
			}
		}
		return dis[t] != dis[0];
	}
	inline ll dfs(ll x, ll ne) {
		if(x == t) return ne;
		ll now = 0, used = 0;
		for(ll i = cur[x]; i; i = edge[i].nxt) {
			cur[x] = i;
			ll v = edge[i].v, e = edge[i].e;
			if(dis[v] == dis[x] + 1 && e) {
				now = dfs(v, min(e, ne - used));
				if(now) {
					edge[i].e -= now;
					edge[i^1].e += now;
					used += now;
					if(used == now) break; 
				}
			}
		}
		return used;
	}
	inline ll Dinic() {
		ll ans = 0;
		while(bfs()) ans += dfs(s, inf);
		return ans;
	}
}F;
vector <pii> Ans;
int main() {
//	freopen(".in", "r", stdin);
//	freopen(".out", "w", stdout);
	ll nl = read(), nr = read(), m = read();
//	assert(nl == 4 && nr == 4 && m == 7);
	F.s = nl + nr + 1, F.t = F.N = F.s + 1;
	for(ll i = 1; i <= nl; i++) F.Addedge(F.s, i, 1);
	for(ll i = nl + 1; i <= nl + nr; i++) F.Addedge(i, F.t, 1);
	for(ll i = 1; i <= m; i++) {
		ll u = read() + 1, v = read() + 1 + nl;
		F.Addedge(u, v, 1);
	}
	ll aans = F.Dinic();
	Ans.reserve(aans);
	write(aans), putchar('\n');
	for(ll i = 1; i <= nl; i++) {
		for(ll j = F.head[i]; j; j = F.edge[j].nxt) if(F.edge[j].v > nl && F.edge[j].v <= nl + nr && !F.edge[j].e) Ans.push_back(mp(i, F.edge[j].v));
	}
	for(auto i : Ans) write(i.fr - 1), putchar(' '), write(i.se - 1 - nl), putchar('\n');
	return 0;
}
/*
*/