#include <bits/stdc++.h>
#define INF 2000000000
#define CARD_MAX 10001
using namespace std;

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

int L[CARD_MAX], R[CARD_MAX], N, M, E;
vector<vector<int>> graph(CARD_MAX, vector<int>());

int dist[CARD_MAX];

bool bfs()
{
    queue<int> Q;

    for(int i = 1; i <= N; ++i)
        if(L[i] == 0)
        {
            dist[i] = 0;
            Q.push(i);
        }
        else dist[i] = INF;

    dist[0] = INF;

    while(!Q.empty())
    {
        int node = Q.front();

        Q.pop();

        if(dist[node] < dist[0])
        {
            for(auto& next : graph[node])
                if(dist[R[next]] == INF)
                {
                    dist[R[next]] = dist[node] + 1;
                    Q.push(R[next]);
                }
        }
    }

    return (dist[0] != INF);
}

bool dfs(int node)
{
    if(node != 0)
    {
        for(auto& next : graph[node])
            if((dist[R[next]] == dist[node] + 1) && dfs(R[next]))
            {
                L[node] = next;
                R[next] = node;
                return true;
            }

        return false;
    }

   return true;
}
int main()
{
    fin >> N >> M >> E;

    for(int x, y, i = 1; i <= E; ++i)
    {
        fin >> x >> y;
        graph[x].push_back(y);
    }

    int cuplaj_maxim = 0;

    while(bfs())
    {
        for(int i = 1; i <= N; ++i)
            if(L[i] == 0 && dfs(i))
                cuplaj_maxim++;
    }

    fout << cuplaj_maxim << "\n";

    for(int i = 1; i <= N; ++i)
        if(L[i] != 0)
            fout << i << " " << L[i] << "\n";
}