#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
using namespace std;

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

vector <int> v[10001];
int c[2001][2001];
int p[2001];

int bfsflux (int s, int t, int p[])
{
    int i, na;
    int flux[2001] = {};
    queue <int> q;

    flux[s] = 1<<30;
    p[s] = -1;
    q.push (s);

    while (q.empty() == 0)
    {
        na = q.front();
        q.pop();

        for (i = 0; i<v[na].size(); i++)
            if (flux[v[na][i]] == 0 && c[na][v[na][i]] > 0)
            {
                flux[v[na][i]] = min (flux[na], c[na][v[na][i]]);
                p[v[na][i]] = na;

                if (v[na][i] == t)
                    return flux[t];

                q.push (v[na][i]);
            }
    }
    return 0;
}

int main()
{
    int n, m, e, i, x, y, flux, rasp, s, t;
    fin >> n >> m >> e;

    for (i = 1; i<=e; i++)
    {
        fin >> x >> y;
        y = y + n;
        v[x].push_back (y);
        v[y].push_back (x);

        c[x][y]++;
    }

    s = 0;
    t = n+m+1;

    for (i = 1; i<=n; i++)
    {
        v[s].push_back (i);
        v[i].push_back (s);

        c[s][i]++;
    }
    for (i = n+1; i<=n+m; i++)
    {
        v[i].push_back (t);
        v[t].push_back (i);

        c[i][t]++;
    }

    rasp = 0;
    do
    {
        flux = bfsflux (s, t, p);
        rasp = rasp + flux;

        x = t;
        while (x != s)
        {
            y = p[x];
            c[y][x] -= flux;
            c[x][y] += flux;
            x = y;
        }

    } while (flux != 0);

    fout << rasp << '\n';
    for (i = 1; i<=n; i++)
        for (int j = 0; j<v[i].size(); j++)
            if (c[v[i][j]][i] == 1 && v[i][j] != s)
            {
                fout << i << ' ' << v[i][j] - n << '\n';
                break;
            }
    return 0;
}