#include <iostream>
#include <fstream>
#include <vector>
#include <limits>
#include <queue>
#include <algorithm>
#include <unordered_set>

using namespace std;

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

int mx = -1, my = -1;

struct Edge
{
    int v, u;
    long long cap, flow = 0;
    Edge(int v, int u, long long cap)
    {
        this->v = v;
        this->u = u;
        this->cap = cap;
    }
};

struct Dinic
{
    vector<vector<int>> adjList;
    vector<Edge> edges;
    vector<int> level, ptr;
    queue<int> q;
    long long flow_inf = numeric_limits<long long>::max();
    int s, t, n, m = 0;

    Dinic(int n, int s, int t, int expect)
    {
        this->s = s;
        this->t = t;
        this->n = n;
        adjList.resize(n);
        level.resize(n);
        ptr.resize(n);
        edges.reserve(expect);
    }

    void addEdge(int v, int u, long long cap = 1)
    {
        edges.emplace_back(v, u, cap);
        edges.emplace_back(u, v, 0);
        adjList[v].push_back(m);
        adjList[u].push_back(m + 1);
        m += 2;
    }

    bool bfs()
    {
        while (q.empty() == false)
        {
            int v = q.front();
            q.pop();
            int siz = static_cast<int>(adjList[v].size());
            for (int i = 0; i < siz; i++)
            {
                int id = adjList[v][i];
                if (level[edges[id].u] != -1 || edges[id].cap - edges[id].flow < 1)
                    continue;
                level[edges[id].u] = level[v] + 1;
                q.push(edges[id].u);
            }
        }
        return level[t] != -1;
    }

    long long dfs(int v, long long pushed)
    {
        if (pushed == 0)
            return 0;
        if (v == t)
            return pushed;
        int siz = static_cast<int>(adjList[v].size());
        for (int &cid = ptr[v]; cid < siz; cid++)
        {
            int id = adjList[v][cid];
            int u = edges[id].u;
            if (level[v] + 1 != level[u] || edges[id].cap - edges[id].flow < 1)
                continue;
            long long tr = dfs(u, min(pushed, edges[id].cap - edges[id].flow));
            if (tr == 0)
                continue;
            edges[id].flow += tr;
            edges[id ^ 1].flow -= tr;
            return tr;
        }
        return 0;
    }

    void solve()
    {
        long long f = 0;
        while (true)
        {
            fill(level.begin(), level.end(), -1);
            q.push(s);
            level[s] = 0;
            if (!bfs())
                break;
            fill(ptr.begin(), ptr.end(), 0);
            while (long long fl = dfs(s, flow_inf))
                f += fl;
        }
        vector<pair<int, int>> sol;
        for (auto a : edges)
        {
            if (a.flow == 1 && a.v != s && a.u != t)
                sol.emplace_back(a.v, a.u);
        }
        fout << sol.size() << "\n";
        for (auto a : sol)
        {
            fout << a.first - 1 << " " << a.second - mx - 1 << "\n";
        }
    }
};

int main()
{
    int n, m, e;
    fin >> n >> m >> e;
    int sink = mx + my + 2;
    Dinic D(n + m + 3, 1, sink, e);
    for (int i = 0; i < e; i++)
    {
        int x, y;
        fin >> x >> y;
        D.addEdge(x + 1, y + n + 1);
    }

    for (int i = 2; i <= n + 1; i++)
    {
        D.addEdge(1, i);
    }
    for (int i = n + 2; i <= n + m + 1; i++)
    {
        D.addEdge(i, sink);
    }
    mx = n;
    D.solve();
    return 0;
}