#include <iostream>
#include <fstream>
#include <cstring>
#include <vector>
#define NMAX 10000
#define MMAX 10000

using namespace std;

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

vector <int> adj[MMAX + 1];
int rgt[MMAX + 1], lft[MMAX + 1];
bool used[MMAX + 1];
int N, M, E, x, y;

bool pairup(int u)
{
    if (used[u] == true) return false;
    used[u] = true;

    for (int w:adj[u])
        if (!rgt[w])
        {
            lft[u] = w;
            rgt[w] = u;
            return true;
        }

    for (int w:adj[u])
        if (pairup(rgt[w]))
        {
            lft[u] = w;
            rgt[w] = u;
            return true;
        }

    return false;
}

int main()
{
    fin >> N >> M >> E;

    for (int i = 1; i <= E; ++i)
    {
        fin >> x >> y;
        adj[x].push_back(y);
    }

    bool ok;
    int pairCount = 0;

    do
    {
        ok = false;
        for (int i = 1; i <= N; ++i)
            used[i] = 0;
        for (int i = 1; i <= N; ++i)
            if (!lft[i] && pairup(i))
                ok = true, pairCount++;
    }
    while (ok == true);

    fout << pairCount << '\n';

    for (int i = 1; i <= N; ++i)
       if (lft[i]) fout << i << " " << lft[i] << '\n';

    fin.close();
    fout.close();
    return 0;
}