// 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;
}
// Heaven and Earth... My guiding star...
// Akira Complex R.I.P.
namespace Dinic
{
    uint To[400005],Last[400005],End[100005],Dist[100005],Cur[100005],n,tp;bol Flow[400005];
    voi build(uint n){Dinic::n=n,tp=0;for(uint i=0;i<n;i++)End[i]=-1;}
    voi insert(uint u,uint v)
    {
        To[tp]=v,Last[tp]=End[u],Flow[tp]=true,End[u]=tp++;
        To[tp]=u,Last[tp]=End[v],Flow[tp]=false,End[v]=tp++;
    }
    bol bfs(uint p,uint t)
    {
        for(uint i=0;i<n;i++)Dist[i]=-1,Cur[i]=End[i];
        Dist[p]=0;std::queue<uint>Q;Q.push(p);
        while(Q.size())
        {
            p=Q.front(),Q.pop();if(p==t)return true;
            for(uint e=End[p];~e;e=Last[e])
                if(Flow[e]&&_min(Dist[To[e]],Dist[p]+1))Q.push(To[e]);
        }
        return false;
    }
    bol dfs(uint p,uint t)
    {
        if(p==t)return true;
        for(uint&e=Cur[p];~e;e=Last[e])if(Flow[e]&&Dist[To[e]]==Dist[p]+1&&dfs(To[e],t))
        	return Flow[e]=false,Flow[e^1]=true;
        return false;
    }
    uint run(uint p,uint t)
    {
        uint ans=0;
        while(bfs(p,t))for(uint e=End[p];~e;e=Last[e])if(Flow[e]&&dfs(To[e],t))Flow[e]=false,ans++;
        return ans;
    }
}
int main()
{
#ifdef MYEE
    freopen("QAQ.in","r",stdin);
    freopen("QAQ.out","w",stdout);
#endif
    uint a,b,m;scanf("%u%u%u",&a,&b,&m),Dinic::build(a+b+2);
    for(uint i=0;i<a;i++)Dinic::insert(a+b,i);
    for(uint i=0;i<b;i++)Dinic::insert(a+i,a+b+1);
    while(m--){uint u,v;scanf("%u%u",&u,&v),Dinic::insert(u,a+v);}
    printf("%u\n",Dinic::run(a+b,a+b+1));
    for(uint e=Dinic::End[a+b];~e;e=Dinic::Last[e])if(!Dinic::Flow[e])
    	for(uint e2=Dinic::End[Dinic::To[e]];~e2;e2=Dinic::Last[e2])if(Dinic::Flow[e2^1])
    		printf("%u %u\n",Dinic::To[e],Dinic::To[e2]-a);
    return 0;
}

// 那就是希望。
// 即便需要取模，也是光明。