#include <fstream>
#include <vector>

const int NMAX = 10005;

using namespace std;

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

int N,M,maxi,E,muchii,x,y;
int L[NMAX],R[NMAX];
vector <int> v[NMAX];
bool change;
bool viz[NMAX];

bool cupleaza(int nod)
{
    if (viz[nod] == true)
        return false;
    viz[nod] = true;

    for (int i = 0; i < v[nod].size(); ++i)
    {
        int vecin = v[nod][i];
        if (!R[vecin])
        {
            L[nod] = vecin;
            R[vecin] = nod;
            return true;
        }
    }

    for (int i = 0; i < v[nod].size(); ++i)
    {
        int vecin = v[nod][i];
        if (cupleaza(vecin))
        {
            L[nod] = vecin;
            R[vecin] = nod;
            return true;
        }
    }

    return false;
}

int main()
{
    f >> N >> M >> E;
    for (int i = 1; i <= E; ++i)
    {
        f >> x >> y;
        v[x].push_back(y);
    }

    maxi = max(N,M);

    change = true;

    while (change)
    {
        change = false;

        for (int i = 1; i <= maxi; ++i)
        {
            viz[i] = false;
        }

        for (int i = 1; i <= N; ++i)
        {
            if (!L[i])
            {
                if (cupleaza(i))
                {
                    change = true;
                }
            }
        }
    }

    for (int i = 1; i <= N; ++i)
    {
        if (L[i])
            muchii++;
    }

    g << muchii << '\n';

    for (int i = 1; i <= N; ++i)
    {
        if (L[i])
        {
            g << i << " " << L[i] << '\n';
        }
    }

    f.close();
    g.close();
    return 0;
}