// 那就是希望。
// 即便需要取模，也是光明。

#include <algorithm>
#include <queue>
#include <stdio.h>
#include <vector>
typedef long long llt;
typedef unsigned uint;typedef unsigned long long ullt;
typedef bool bol;typedef char chr;typedef void voi;
typedef double dbl;
template<typename T>bol _max(T&a,T b){return(a<b)?a=b,true:false;}
template<typename T>bol _min(T&a,T b){return(b<a)?a=b,true:false;}
template<typename T>T lowbit(T n){return n&-n;}
template<typename T>T gcd(T a,T b){return b?gcd(b,a%b):a;}
template<typename T>T lcm(T a,T b){return(a!=0||b!=0)?a/gcd(a,b)*b:(T)0;}
template<typename T>T exgcd(T a,T b,T&x,T&y){if(b!=0){T ans=exgcd(b,a%b,y,x);y-=a/b*x;return ans;}else return y=0,x=1,a;}
template<typename T>T power(T base,T index,T mod)
{
    T ans=1%mod;
    while(index)
    {
        if(index&1)ans=ans*base%mod;
        base=base*base%mod,index>>=1;
    }
    return ans;
}
namespace Dinic
{
	uint n;
	uint To[500005],Last[500005],tp;ullt Flow[500005];
	uint End[500005],Cur[500005],Dep[500005];
	voi bzr(uint n){Dinic::n=n,tp=0;for(uint i=0;i<n;i++)End[i]=-1;}
	voi insert(uint u,uint v,ullt f){
		To[tp]=v,Last[tp]=End[u],Flow[tp]=f,End[u]=tp++;
		To[tp]=u,Last[tp]=End[v],Flow[tp]=0,End[v]=tp++;
	}
	bol bfs(uint p,uint t){
		for(uint i=0;i<n;i++)Cur[i]=End[i],Dep[i]=-1;
		std::queue<uint>Q;Q.push(p),Dep[p]=0;
		while(Q.size()){
			p=Q.front(),Q.pop();
			for(uint e=End[p];~e;e=Last[e])
				if(Flow[e]&&_min(Dep[To[e]],Dep[p]+1))Q.push(To[e]);
		}
		return~Dep[t];
	}
	ullt dfs(uint p,uint t,ullt f){
		if(p==t)return f;
		ullt ans=0;
		for(uint&e=Cur[p];~e;e=Last[e])if(Flow[e]&&Dep[To[e]]==Dep[p]+1){
			ullt g=dfs(To[e],t,std::min(f,Flow[e]));
			Flow[e]-=g,f-=g,Flow[e^1]+=g,ans+=g;
			if(!f)return ans;
		}
		return ans;
	}
	ullt run(uint s,uint t){
		ullt ans=0;
		while(bfs(s,t))ans+=dfs(s,t,-1);
		return ans;
	}
}
int main()
{
#ifdef MYEE
    freopen("QAQ.in","r",stdin);
    freopen("QAQ.out","w",stdout);
#endif
	uint l,r,m;scanf("%u%u%u",&l,&r,&m),Dinic::bzr(l+r+2);
	for(uint i=0;i<l;i++)Dinic::insert(l+r,i,1);
	for(uint i=0;i<r;i++)Dinic::insert(l+i,l+r+1,1);
	while(m--){uint u,v;scanf("%u%u",&u,&v),Dinic::insert(u,l+v,1);}
	printf("%llu\n",Dinic::run(l+r,l+r+1));
	for(uint i=0;i<l;i++)if(Dinic::Flow[i<<1|1])
		for(uint e=Dinic::End[i];~e;e=Dinic::Last[e])if(!Dinic::Flow[e])
			printf("%u %u\n",i,Dinic::To[e]-l);
    return 0;
}

// 那就是希望。
// 即便需要取模，也是光明。