#include <iostream>
#include <fstream>
#include <queue>
#include <algorithm>

using namespace std;

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

int const nmax = 10000;

int n, m, e;
int dist[1 + 2 * nmax];
bool vis[1 + 2 * nmax];
vector<int> g[1 + 2 * nmax];
int match[1 + 2 * nmax];

void addedge(int x, int y)
{
    g[x].push_back(y);
    g[y].push_back(x);
}

void bfs()
{
    fill(dist + 1, dist + n + m + 1, -1);
    queue < int > q;
    for(int i = 1; i <= n; i++)
    {
        if(match[i] <= 0)
        {
            q.push(i);
            dist[i] = 0;
        }
    }

    //u, u1, u2, noduri din stanga si v, v1, v2 noduri din dreapta
    while(!q.empty())
    {
        int u1 = q.front();
        q.pop();
        for(int i = 0; i < g[u1].size(); i++)
        {
            int v1 = g[u1][i];
            int u2 = match[v1]; //prin matching
            if(0 < u2 && dist[u2] < 0)
            {
                dist[u2] = dist[u1] + 1;
                q.push(u2);
            }
        }
    }
}

bool dfs(int u1)
{
    vis[u1] = 1;
    for(int i = 0; i < g[u1].size(); i++)
    {
        int v1 = g[u1][i];
        int u2 = match[v1];
        if(match[v1] <= 0)
        {
            match[u1] = v1;
            match[v1] = u1;
            return true;
        }
        else if(vis[u2] == 0 && dist[u2] == dist[u1] + 1)
        {
            if(dfs(u2) == 1)
            {
                match[u1] = v1;
                match[v1] = u1;
                return true;
            }
        }
    }
    return false;
}

int maxmatching()
{
    int answer = 0, add = 1;
    while(0 < add)
    {
        bfs();
        fill(vis + 1, vis + n + m + 1, false);

        add = 0;
        for(int i = 1; i <= n; i++)
        {
            if(match[i] <= 0)
            {
                if(dfs(i) == true)
                    add++;
            }
        }
        answer += add;
    }
    return answer;
}

int main()
{
    in >> n >> m >> e;
    for(int i = 1; i <= e; i++)
    {
        int x, y;
        in >> x >> y;
        addedge(x, y + n);
    }
    out << maxmatching() << '\n';
    for(int i = 1; i <= n; i++)
    {
        if(0 < match[i])
        {
            out << i << ' ' << match[i] - n << '\n';
        }
    }

    in.close();
    out.close();
    return 0;
}