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

#define NMAX        10009
#define MMAX        200009
#define kInf        (1 << 30)
#define kInfLL      (1LL << 60)
#define kMod        666013
#define edge pair<int, int>
#define x first
#define y second

#define USE_FILES "MLC"

#ifdef USE_FILES
#define cin fin
#define cout fout
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
#endif

// 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

// returneaza 1 daca node a fost cuplat
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(); // reset all
        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
    visited.reset(); // reset all
    memset(left2right, 0, sizeof(left2right));
    memset(right2left, 0, sizeof(right2left));

    for (int i = 1; i <= n; ++i) {
        if (G[i].size())  {
            G[i].clear();
        }
    }

    // clean every shit
    n = m = e = sol = 0;
}

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

    return 0;
}