#include <iostream>
#include <fstream>
#include <vector>

using namespace std;

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

const int SIZE = 10005;

int l, r, n;
int st[SIZE], dr[SIZE];

vector <int> adj[SIZE];
vector <bool> visited(SIZE, false);

void Read()
{
    f >> l >> r >> n;
    for (int i = 1; i <= n; i++)
    {
        int x, y;
        f >> x >> y;
        adj[x].push_back(y);
    }
}

bool PairUp(int node)
{
    if (visited[node] == true)  return false;

    visited[node] = true;
    for (unsigned int i = 0; i < adj[node].size(); i++)
    {
        int neighbour = adj[node][i];
        if (dr[neighbour] == 0)
        {
            st[node] = neighbour;
            dr[neighbour] = node;
            return true;
        }
    }

    for (unsigned int i = 0; i < adj[node].size(); i++)
    {
        int neighbour = adj[node][i];
        if (PairUp(dr[neighbour]) == true)
        {
            st[node] = neighbour;
            dr[neighbour] = node;
            return true;
        }
    }

    return false;
}

void Solve()
{
    while (true)
    {
        fill(visited.begin(), visited.end(), false);
        bool ok = false;

        for (int i = 1; i <= l; i++)
        {
            if (st[i] == 0 && PairUp(i) == true)
            {
                ok = true;
            }
        }

        if (ok == false)
        {
            return;
        }
    }
}

void Print()
{
    vector < pair <int, int> > ans;

    for (int i = 1; i <= l; i++)
    {
        if (st[i] != 0)
        {
            ans.push_back(make_pair(i, st[i]));
        }
    }

    g << ans.size() << "\n";
    for (unsigned int i = 0; i < ans.size(); i++)
    {
        g << ans[i].first << " " << ans[i].second << "\n";
    }
}

int main()
{
    Read();
    Solve();
    Print();

    return 0;
}