#include <fstream>
#include <vector>
#include <queue>
#include <unordered_map>
#define VAL 20005
#define INF 1000000000
#define F first
#define S second

using namespace std;

ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");

int N, M, K, i, j, X, be, en;
int prec[VAL], cop, ANS, nod;
bool viz[VAL];
string s[VAL], P;
pair <int, int> MC[VAL];
vector <int> G[VAL];
vector <int> :: iterator it;
unordered_map <string, int> flux;
queue <int> Q;

bool BFS()
{
    for (i=1; i<=en; i++)
      viz[i]=false;
    Q.push(be);
    viz[be]=true;
    while (Q.empty()==false)
    {
        nod=Q.front();
        Q.pop();
        if (nod==en)
          continue;
        for (i=0; i<G[nod].size(); i++)
        {
            P=s[nod]+','+s[G[nod][i]];
            if (viz[G[nod][i]]==false && flux[P]==1)
            {
                viz[G[nod][i]]=true;
                prec[G[nod][i]]=nod;
                Q.push(G[nod][i]);
            }
        }
    }
    return viz[en]==true;
}

void MaxFlow()
{
    while (BFS()==true)
    {
        for (j=0; j<G[en].size(); j++)
        {
            prec[en]=G[en][j];
            X=INF;
            for (i=en; i!=be; i=prec[i])
            {
                P=s[prec[i]]+','+s[i];
                X=min(X, flux[P]);
            }
            if (X==0)
              continue;
            for (i=en; i!=be; i=prec[i])
            {
                P=s[prec[i]]+','+s[i];
                flux[P]-=X;
                P=s[i]+','+s[prec[i]];
                flux[P]+=X;
            }
            ANS+=X;
        }
    }
}

int main()
{
    fin >> N >> M >> K;
    for (i=1; i<=N+M+2; i++)
    {
        cop=i;
        while (cop!=0)
        {
            s[i]+=(cop % 10)+'0';
            cop/=10;
        }
    }
    for (i=1; i<=K; i++)
    {
        fin >> MC[i].F >> MC[i].S;
        MC[i].S+=N;
        G[MC[i].F].push_back(MC[i].S);
        G[MC[i].S].push_back(MC[i].F);
        P=s[MC[i].F]+','+s[MC[i].S];
        flux[P]=1;
    }
    be=N+M+1;
    en=N+M+2;
    for (i=1; i<=N; i++)
    {
        P=s[be]+','+s[i];
        flux[P]=1;
        G[be].push_back(i);
        G[i].push_back(be);
    }
    for (i=N+1; i<=N+M; i++)
    {
        P=s[i]+','+s[en];
        flux[P]=1;
        G[en].push_back(i);
        G[i].push_back(en);
    }
    MaxFlow();
    fout << ANS << '\n';
    for (i=1; i<=K; i++)
    {
        P=s[MC[i].F]+','+s[MC[i].S];
        if (flux[P]==0)
          fout << MC[i].F << " " << MC[i].S-N << '\n';
    }
    fin.close();
    fout.close();
    return 0;
}