#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
#define int long long
using namespace std;

int n,m,cnt=1;
int h[200005];
int cur[200005];
int dep[200005];
bool mp[200005];
struct node{int v,nxt,c;}edge[4000005];

inline void addedge(int u,int v,int c){
	edge[++cnt]={v,h[u],c};
	h[u]=cnt;
	edge[++cnt]={u,h[v],0};
	h[v]=cnt;
	return ;
}

inline bool bfs(int S,int T){
	memset(dep,-1,sizeof(dep));
	dep[S]=0;
	queue <int> q;
	q.push(S);
	while(!q.empty()){
		int u=q.front();
		q.pop();
		for(int i=h[u];i;i=edge[i].nxt){
			int v=edge[i].v;
			if(edge[i].c&&dep[v]==-1){
				dep[v]=dep[u]+1;
				q.push(v);
			}
		}
	}
	return (dep[T]!=-1);
}

inline int dfs(int u,int T,int flow){
	if(u==T||!flow) return flow;
	int res=0;
	mp[u]=1;
	for(int i=cur[u];i;i=edge[i].nxt){
		cur[u]=i;
		int v=edge[i].v;
		if(mp[v]||!edge[i].c||dep[v]!=dep[u]+1) continue;
		int d=dfs(v,T,min(flow,edge[i].c));
		res+=d;
		edge[i].c-=d;
		edge[i^1].c+=d;
		flow-=d;
	}
	mp[u]=0;
	return res;
}

inline int Dinic(int S,int T){
	int f=0;
	while(bfs(S,T)){
		for(int i=1;i<=n;i++) cur[i]=h[i];
		f+=dfs(S,T,1e18);
	}
	return f;
}

inline void in(int &n){
	n=0;
	char c=getchar();
	while(c<'0' || c>'9') c=getchar();
	while(c>='0'&&c<='9') n=n*10+c-'0',c=getchar();
	return ;
}

signed main(){
	int L,R;
	in(L),in(R),in(m);
	int s=L+R+1,t=s+1;
	n=t;
	for(int i=1;i<=m;i++){
		int u,v;
		in(u),in(v);
		u++,v++;
		v+=L;
		addedge(u,v,1);
	}
	for(int i=1;i<=L;i++) addedge(s,i,1);
	for(int i=L+1;i<=L+R;i++) addedge(i,t,1);
	printf("%lld\n",Dinic(s,t));
	for(int i=h[s];i;i=edge[i].nxt){
		int v=edge[i].v;
		if(edge[i].c==0){
			printf("%lld ",v-1);
			for(int j=h[v];j;j=edge[j].nxt){
				int vv=edge[j].v;
				if(edge[j].c==0&&vv<=L+R){
					printf("%lld\n",vv-L-1);
					puts("");
					break;
				}
			}
		}
	}

	return 0;
}