#include <bits/stdc++.h>

const int MAX_N = 10000;

using namespace std;

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

int n, m, e;
int l[MAX_N + 5], r[MAX_N + 5];
bool visited[MAX_N + 5];

vector<int> G[MAX_N + 5];

bool cuplaj(int u) {
    if (visited[u])
        return 0;

    visited[u] = 1;

    for (int v : G[u])
        if (r[v] == 0) {
            l[u] = v;
            r[v] = u;
            return 1;
        }

    for (int v : G[u])
        if (cuplaj(r[v])) {
            l[u] = v;
            r[v] = u;
            return 1;
        }

    return 0;
}

int main() {
    fin >> n >> m >> e;
    for (int i = 1; i <= e; i++) {
        int u, v;
        fin >> u >> v;
        G[u].push_back(v);
    }

    bool ok;
    do {
        ok = 0;
        memset(visited, 0, sizeof(visited));
        for (int i = 1; i <= n; i++)
            if (l[i] == 0)
                ok |= cuplaj(i);
    } while(ok);

    int cuplaj_max = 0;
    for (int i = 1; i <= n; i++)
        cuplaj_max += (l[i] > 0);

    fout << cuplaj_max << '\n';

    for (int i = 1; i <= n; i++)
        if (l[i] > 0)
            fout << i << ' ' << l[i] << '\n';

    return 0;
}