#include <bits/stdc++.h>
using namespace std;
ifstream f ("cuplaj.in");
ofstream g ("cuplaj.out");
const int NMax=10003;
int n,m,k,x,y,ok=true,sol,viz[NMax],vL[NMax],vR[NMax];
vector <int> G[NMax];
bool cuplaj(int nod)
{
    if(viz[nod]) return 0;
    viz[nod]=1;
    for(int i=0;i<G[nod].size();++i)
    {
        if(!vL[G[nod][i]]||cuplaj(vL[G[nod][i]]))
        {
            vR[nod]=G[nod][i];
            vL[G[nod][i]]=nod;
            return 1;
        }
    }
    return 0;
}
int main()
{
    f>>n>>m>>k;
    for(int i=1;i<=k;++i)
    {
        f>>x>>y;
        G[x].push_back(y);
    }
    while(ok)
    {
        ok=false;
        memset(viz,0,sizeof(viz));
        for(int i=1;i<=n;++i)
        {
            if(!vR[i])
            {
                if(cuplaj(i)) ok=true;
            }
        }
    }
    for(int i=1;i<=n;++i) if(vR[i]) ++sol;
    g<<sol<<'\n';
    for(int i=1;i<=n;++i) if(vR[i]) g<<i<<' '<<vR[i]<<'\n';
    return 0;
}