#include <bits/stdc++.h>
using namespace std;
#define For(Ti,Ta,Tb) for(auto Ti=(Ta);Ti<=(Tb);++Ti)
#define Dec(Ti,Ta,Tb) for(auto Ti=(Ta);Ti>=(Tb);--Ti)
#define debug(...) fprintf(stderr,__VA_ARGS__)
#define range(Tx) begin(Tx),end(Tx)
using ll=long long;
struct MaxFlow{
	const int n;
	struct Edge{
		int v;
		ll w;
	};
	vector<Edge> e;
	vector<vector<int>> g;
	MaxFlow(int n):n(n),g(n){}
	void add_edge(int u,int v,ll w){
		g[u].push_back(e.size());
		e.push_back({v,w});
		g[v].push_back(e.size());
		e.push_back({u,0});
	}
	vector<int> dis,now;
	bool bfs(int s,int t){
		dis.assign(n,int(1e9));
		queue<int> q;
		dis[s]=0;
		q.push(s);
		while(q.size()){
			int u=q.front();
			q.pop();
			for(int i:g[u]){
				if(e[i].w&&dis[e[i].v]==int(1e9)){
					dis[e[i].v]=dis[u]+1;
					q.push(e[i].v);
					if(e[i].v==t){
						return 1;
					}
				}
			}
		}
		return 0;
	}
	ll dinic(int u,int t,ll flow){
		if(u==t){
			return flow;
		}
		ll rest=flow;
		for(int i=now[u];i<int(g[u].size())&&rest;++i){
			now[u]=i;
			int j=g[u][i];
			auto [v,w]=e[j];
			if(w&&dis[v]==dis[u]+1){
				ll k=dinic(v,t,min(rest,w));
				if(!k){
					dis[v]=-1;
				}else{
					e[j].w-=k;
					e[j^1].w+=k;
					rest-=k;
				}
			}
		}
		return flow-rest;
	}
	ll flow(int s,int t){
		ll ans=0;
		while(bfs(s,t)){
			now.assign(n,0);
			ans+=dinic(s,t,numeric_limits<ll>::max());
		}
		return ans;
	}
	auto edges() const{
		vector<tuple<int,int,ll>> res;
		for(int i=0;i<int(e.size());i+=2){
			res.emplace_back(e[i^1].v,e[i].v,e[i].w);
		}
		return res;
	}
};
int main(){
	cin.tie(nullptr)->sync_with_stdio(false);
	int n1,n2,m;
	cin>>n1>>n2>>m;
	MaxFlow f(n1+n2+2);
	int s=f.n-2,t=f.n-1;
	For(i,0,n1-1){
		f.add_edge(s,i,1);
	}
	For(i,n1,n1+n2-1){
		f.add_edge(i,t,1);
	}
	For(i,1,m){
		int u,v;
		cin>>u>>v;
		f.add_edge(u,v+n1,1);
	}
	cout<<f.flow(s,t)<<'\n';
	auto edges=f.edges();
	for(auto [u,v,w]:edges){
		if(max(u,v)<n1+n2&&!w){
			cout<<u<<' '<<v-n2<<'\n';
		}
	}
	return 0;
}