// https://goo.gl/fBmFxu
#include <bits/stdc++.h>
using namespace std;

#define NMAX        10009

// number of tests from "in"
int test_cnt = 1;
void clean_test();

int n, m, e;
vector<int> G[NMAX];
bitset<NMAX> visited;

int sol;              // dimensiunea cuplajului
int left2right[NMAX]; // i -> left2right[i]
int right2left[NMAX];  // right2left[i] <- i


int dfs(int node) {
    if (visited[node]) {
        return 0;
    }

    visited[node] = 1; // visited

    // cupleaza-l fara sa modifici cuplajul existent
    for (auto &x : G[node]) { // node -> x
        if (!right2left[x]) {
            left2right[node] = x;
            right2left[x] = node;
            return 1;
        }
    }

    // cupleaza-l, recupland mai intai alt nod
    for (auto &x : G[node]) { // node -> x, right2left[x] <- x
        if (right2left[x] && dfs(right2left[x])) {
            left2right[node] = x;
            right2left[x] = node;
            return 1;
        }
    }

    // buba
    return 0;
}

void do_maximum_matching() {
    sol = 0; // solutia

    bool done = false;
    while (!done) {
        done = true;

        visited.reset();
        for (int i = 1; i <= n; ++i) {
            if (!left2right[i] && dfs(i)) {
                ++sol;
                done = false;
            }
        }
    }
}

void solve() {
    cin >> n >> m >> e;

    for (int i = 1; i <= e; ++i) {
        int x, y;
        cin >> x >> y;
        G[x].push_back(y);
    }

    do_maximum_matching();

    cout << sol << "\n";
    for (int i = 1; i <= n; ++i) {
        if (left2right[i]) {
            cout << i << " " << left2right[i] << "\n";
        }
    }

    if (test_cnt > 0) {
        clean_test();
    }
}


void clean_test() {
    // clean if needed
    for (int i = 1; i <= n; ++i) {
        visited[i] = 0;
        left2right[i] = 0;
        right2left[i] = 0;

        if (G[i].size())  {
            G[i].clear();
        }
    }

    n = m = e = sol = 0;
}

int main() {
    // din cauza ca fac redirectari, salvez starea lui cin si cout
    auto cin_buff = cin.rdbuf();
    auto cout_buff = cout.rdbuf();

    // las liniile urmatoare daca citesc din fisier
    ifstream fin("in");
    cin.rdbuf(fin.rdbuf()); // save and redirect

    // las liniile urmatoare daca afisez in fisier
//     ofstream fout("out");
//     cout.rdbuf(fout.rdbuf()); // save and redirect


//    cin >> test_cnt;
    while (test_cnt--) {
        solve();
    }

    // restore pentru cin si cout
    cin.rdbuf(cin_buff);
    cout.rdbuf(cout_buff);

    return 0;
}