#include <fstream>
#include <vector>
using namespace std;
ifstream cin ("cuplaj.in");
ofstream cout ("cuplaj.out");
vector <int> lista[10005];
int lover[10005];
int loverman[10005];
int viz[10005];
int bkt(int dani)
{
    if (viz[dani])
        return 0;
    viz[dani] = 1;
    for (int i = 0; i < lista[dani].size(); i++)
    {
        int iulia = lista[dani][i];
        if (!loverman[iulia] || bkt(loverman[iulia]))
        {
            loverman[iulia] = dani;
            lover[dani] = iulia;
            return 1;
        }
    }
    return 0;
}
int main()
{
    int ans = 0, n, i, m, e;
    cin >> n >> m >> e;
    for (i = 1; i <= e; i++)
    {
        int x, y;
        cin >> x >> y;
        lista[x].push_back(y);
    }
    int nr = 1;
    while (nr)
    {
        for (i = 1; i <= n; i++)
            viz[i] = 0;
        nr = 0;
        for (i = 1; i <= n; i++)
            if (!lover[i])
                nr += bkt(i);
    }
    for (i = 1; i <= n; i++)
        if (lover[i])
            ans++;
    cout << ans;
    for (i = 1; i <= n; i++)
        if (lover[i])
        cout << '\n' << i << " " << lover[i];

    return 0;
}