#include <bits/stdc++.h>
using namespace std;

ifstream f("cuplaj.in");
ofstream g("cuplaj.out");

typedef struct
{
    int start;
    int finish;
} legatura;


typedef struct
{
    int flow;
    int capacitate;
} dual;

typedef struct
{
    int val;
    bool out;

} vecin;

int n1,n2,m;
int nr_noduri,n;
vector<vector<vecin>> lista_adiacenta;
vector<int> tata;
dual matrice[1001][1001];
vector<int> taietura;
vector<legatura> solutie;
vector<int> vizitat_global;

void citire()
{
    f >> n1 >> n2 >> m;
    nr_noduri = n1+n2;
    n = nr_noduri+1;
    lista_adiacenta.reserve(n+1);
    vizitat_global.resize(n+1,false);
    int i;
    for(i=0;i<=n;i++)
    {
        vector<vecin> aux;
        lista_adiacenta.push_back(aux);
    }

    for(i=1;i<=n1;i++)
    {
        matrice[0][i].capacitate = 1;
        matrice[0][i].flow = 0;

        lista_adiacenta[0].push_back({i,true});
        lista_adiacenta[i].push_back({0,false});
    }

    for(i=1;i<=n2;i++)
    {
        int aux = n1+i;
        matrice[aux][n].capacitate = 1;
        matrice[aux][n].flow = 0;

        lista_adiacenta[aux].push_back({n,true});
        lista_adiacenta[n].push_back({aux,false});
    }


    int x,y,poz2;
    for(i=1;i<=m;i++)
    {
        f>>x>>y;
        poz2 = n1 + y;
        //cout << "afisare: " << x<< " -> " << poz2 << endl;
        matrice[x][poz2].capacitate = 1;
        matrice[x][poz2].flow = 0;
        matrice[poz2][x].capacitate = 1;
        matrice[poz2][x].flow = 0;

        lista_adiacenta[x].push_back({poz2,true});
        lista_adiacenta[poz2].push_back({x,false});
    }
}

bool BFS()
{
    taietura.clear();
    taietura.reserve(n);
    taietura.push_back(1);
    //cout << "\n\n\nBFS\n\n\n";
    queue<int> coada;
    tata.clear();
    tata.resize(n+1, 0);
    vector<bool> vizitat;
    vizitat.resize(n+1, false);

    coada.push(0);
    vizitat[0] = true;

    int curent;
    int destinatie;
    int rezidual;

    while(!coada.empty())
    {
        curent = coada.front();
        coada.pop();

        for(auto &it : lista_adiacenta[curent])
        {
            destinatie = it.val;
            if(!vizitat[destinatie] && !vizitat_global[destinatie])
            {
                if(it.out)
                {

                    // daca este nod care iese din curent
                    rezidual = matrice[curent][destinatie].capacitate - matrice[curent][destinatie].flow;
                    if(rezidual > 0)
                    {
                        tata[destinatie] = curent;
                        vizitat[destinatie] = true;
                        coada.push(destinatie);

                        taietura.push_back(destinatie);
                        //cout << curent << " -> " << destinatie << "  = " << rezidual << endl;
                        if(destinatie == n)
                            {
                                return true;
                            }
                    }

                }
                else
                {
                    // daca este nod care intra in curent
                    rezidual = matrice[destinatie][curent].flow;
                    if(rezidual > 0)
                    {

                        tata[destinatie] = -curent;
                        vizitat[destinatie] = true;
                        coada.push(destinatie);

                        taietura.push_back(destinatie);
                        //cout << destinatie << " ====> " << curent << "   = " << rezidual << endl;
                        if(destinatie == n)
                            return true;
                    }

                }



            }

        }

    }

    return false;



}


void revizuieste()
{

    //cout << "\n\n\n\nREVIZUIRE\n\n\n";
    int curent = n;
    int t = tata[n];
    int rezidual;
    int minim = 999999;

    // variabile pt adaugare legaturi cuplaj
    int sfarsit,inceput;
    sfarsit = tata[n];
    if(sfarsit < 0)
        sfarsit = -sfarsit;
    inceput = tata[sfarsit];
    if(inceput < 0)
        inceput = -inceput;

    //cout << " inceput : " << inceput  << " --- sfarsit : " << sfarsit << endl;
    sfarsit -= n1;
    solutie.push_back({inceput,sfarsit});

    while(curent!=0)
    {
        if(t < 0)
        {
            rezidual = matrice[curent][-t].flow;
            t = -t;
            //if(rezidual == 0)
                //cout << -t << " -> " << curent << endl;
        }
        else
            rezidual = matrice[t][curent].capacitate - matrice[t][curent].flow;

        //cout << t << " -> " << curent << endl;
        minim = min(rezidual,minim);
        curent = t;
        if(curent != 0)
            t = tata[curent];
    }

    curent = n;
    t = tata[n];

    while(curent!=0)
    {
        if(t < 0)
        {
            t = -t;
            matrice[curent][t].flow -= minim;
        }
        else
            matrice[t][curent].flow += minim;

        curent = t;
        if(curent!=0)
        t = tata[curent];
    }






}






int main()
{
    citire();
    while(BFS())
        revizuieste();

/*
    cout << "TAIETURA MINIMA:\n";
    for(int& nod : taietura)
        cout << nod << " ";
    cout << endl << endl << endl;
*/

    g << solutie.size() << endl;
    for(auto &leg : solutie)
        g << leg.start << " " << leg.finish << endl;

}