#include <bits/stdc++.h>

using namespace std;

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

int n, m, muchii, c[10001][10001], tata[10001];
vector <int> vecini[10001];

bool bfs(int s, int t)
{
    for (int i=s;i<=t;i++)
        tata[i] = -1;

    queue <int> q;
    q.push(s);
    tata[s] = 0;

    while (!q.empty())
    {
        int i = q.front();
        q.pop();

        for (auto j : vecini[i])
            if (c[i][j] and tata[j] == -1)
        {
            tata[j] = i;

            if (j == t)
                return true;

            q.push(j);
        }
    }
    return false;
}

int EdmondsKarp (int s, int t)
{
    int fluxMaxim = 0;

    while (bfs(s, t))
    {
        int fluxCurent = INT_MAX;

        for (int j = t; j != s; j = tata[j])
        {
            int i = tata[j];
            fluxCurent = min(fluxCurent, c[i][j]);
        }

        for (int j = t; j != s; j = tata[j])
        {
            int i = tata[j];
            c[i][j] -= fluxCurent;
            c[j][i] += fluxCurent;
        }

        fluxMaxim += fluxCurent;
    }
    return fluxMaxim;
}

bool is_vecin (int x, int y)
{
    for (auto i : vecini[x])
        if (i == y)
            return true;
    return false;
}

int main()
{
    f>>n>>m>>muchii;

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

    for (int i=1;i<=n;i++)
    {
        vecini[s].push_back(i);
        vecini[i].push_back(s);
        c[s][i] = 1;
    }

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

    for (int i=1;i<=muchii;i++)
    {
        int x,y;
        f>>x>>y;
        vecini[x].push_back(n + y);
        vecini[n + y].push_back(x);
        c[x][n + y] = 1;
    }

    g<<EdmondsKarp(s, t)<<'\n';

    for (int i=1;i<=n;i++)
        for (int j=n+1;j<=n+m;j++)
            if (c[i][j] == 0 and is_vecin(i, j))
                g<<i<<" "<<j - n<<'\n';
}