#include <cstring>
#include <fstream>
#include <vector>

constexpr auto max_n = 10005;

using namespace std;

FILE* fin;
FILE* fout;

vector<vector<int>> graph;
vector<int> l;
vector<int> r;
int n, m, e;
vector<bool> visited;

bool pairup(const int node)
{
    if (visited[node])
        return false;

    visited[node] = true;

    for (auto neigh : graph[node])
    {
        if (r[neigh])
            continue;

        l[node] = neigh;
        r[neigh] = node;

        return true;
    }

    for (auto neigh : graph[node])
    {
        if (pairup(r[neigh]))
        {
            l[node] = neigh;
            r[neigh] = node;

            return true;
        }
    }

    return false;
}

int main()
{
    fin = fopen("cuplaj.in", "r");
    fout = fopen("cuplaj.out", "w");

    fscanf(fin, "%d %d %d", &n, &m, &e);

    l.resize(n + 1, 0);
    r.resize(m + 1, 0);

    graph.resize(n + 1);

    for (auto i = 0; i < e; i++)
    {
        int x, y;
        fscanf(fin, "%d %d", &x, &y);
        graph[x].push_back(y);
    }

    auto has_solution = true;
    while (has_solution)
    {
        has_solution = false;

        visited.clear();
        visited.resize(n + 1, false);

        for (auto i = 1; i <= n; i++)
            if (!l[i])
                has_solution = has_solution || pairup(i);
    }

    auto result = 0;

    for (auto i = 1; i <= n; i++)
        if (l[i] > 0)
            result++;

    fprintf(fout, "%d\n", result);
    
    for (auto i = 1; i <= n; i++)
        if (l[i] > 0)
            fprintf(fout, "%d %d\n", i, l[i]);
            
    return 0;
}