#include <fstream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <map>
#include <unordered_map>
#include <set>
#include <cstring>
#include <chrono>
#include <cassert>
#include <bitset>
#include <stack>
#include <queue>
#include <iomanip>
#include <random>
#include <string>
#include <complex>
//#include <ext/pb_ds/assoc_container.hpp>

#ifdef _MSC_VER
#  include <intrin.h>
#  define __builtin_popcount __popcnt
#  define __builtin_popcountll __popcnt64
#endif

#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#define x first
#define y second
#define ld long double
#define ll long long
#define ull unsigned long long
#define us unsigned short
#define lsb(x) ((x) & (-(x)))
#define pii pair <int, int>
#define pll pair <ll, ll>

using namespace std;
//using namespace __gnu_pbds;

mt19937_64 gen(time(0));
uniform_int_distribution <int64_t> rng;

#ifdef  LOCAL
ifstream cin("test.in");
ofstream cout("test.out");
#else
ifstream cin("cuplaj.in");
ofstream cout("cuplaj.out");
#endif

const int N = 20000;

struct Flow {
    struct Edge {
        int to;
        bool cap;
        int ind;
    };
    int n;

    int lvl[N + 5], idx[N + 5];
    bitset <N + 5> cap[N + 5];
    vector <Edge> g[N + 5];

    void init(int _n) {
        n = _n;

        for (int i = 1; i <= n; i++)
            g[i].clear();
    }

    void add_edge(int x, int y, bool z) {
        g[x].push_back({ y, z, (int)g[y].size() });
        g[y].push_back({ x, 0, (int)g[x].size() - 1 });
    }

    bool bfs(int src, int dst) {
        queue <int> q;
        memset(lvl, 0, sizeof(lvl));
        lvl[src] = 1;
        q.push(src);

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

            int ind = 0;
            for (auto &[son, cap, _] : g[node]) {
                if (!lvl[son] && cap > 0) {
                    lvl[son] = lvl[node] + 1;
                    q.push(son);
                }
            }
        }

        return lvl[dst] > 0;
    }

    int dfs(int node, int dst, int flow = (int)1e9) {
        if (node == dst)
            return flow;
        for (; idx[node] < g[node].size(); idx[node]++) {
            auto& [son, cap, ind] = g[node][idx[node]];
            if (cap <= 0 || lvl[son] != lvl[node] + 1)
                continue;

            int new_flow = dfs(son, dst, cap);

            if (new_flow) {
                cap -= new_flow;
                g[son][ind].cap += new_flow;
                return new_flow;
            }
            lvl[son] = 0;
        }
        return 0;
    }

    int max_flow(int src, int dst) {
        int total_flow = 0, flow;

        while (bfs(src, dst)) {
            memset(idx, 0, sizeof(idx));
            while(flow = dfs(src, dst)) {
                total_flow += flow;
            }
        }

        return total_flow;
    }
} flow;

int n, m, e;
map <pii, bool> edges;

void solve(int test) {
    ld t1 = clock();
    cin >> n >> m >> e;
    flow.init(n + m + 2);
    int src = n + m + 1, dst = n + m + 2;
    for (; e; e--) {
        int x, y;
        cin >> x >> y;
        edges[make_pair(x, y)] = 1;
        flow.add_edge(x, y + n, 1);
    }
    for (int i = 1; i <= n; i++)
        flow.add_edge(src, i, 1);
    for (int i = 1; i <= m; i++)
        flow.add_edge(n + i, dst, 1);
    cout << flow.max_flow(src, dst) << "\n";
    for (int i = 1; i <= n; i++) {
        for (auto& [j, cap, _] : flow.g[i]) {
            if(cap == 0 && edges.find(make_pair(i, j - n)) != edges.end())
                cout << i << " " << j - n << '\n';
        }
    }
#ifdef LOCAL
    cout << (clock() - t1) / CLOCKS_PER_SEC << "s\n";
#endif
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    srand(time(0));

    int T = 1;
    //cin >> T;

    for (int t = 1; t <= T; t++) {
        solve(t);
    }

    return 0;
}