#include <bits/stdc++.h>

using namespace std;

#define int int64_t

const int inf = 2e18;
const int mod = 1e9 + 7;

vector<vector<int>> g;
vector<int> p;
vector<bool> used;

bool dfs(int v) {
    used[v] = true;
    for (int to: g[v]) {
        if (p[to] == -1 || !used[p[to]] && dfs(p[to])) {
            p[to] = v;
            return true;
        }
    }
    return false;
}

int32_t main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    int n1, n2, m;
    cin >> n1 >> n2 >> m;
    g.resize(n1);
    for (int i = 0; i < m; i++) {
        int a, b;
        cin >> a >> b;
        a--;
        b--;
        g[a].push_back(b);
    }
    p.assign(n2, -1);
    int ans = 0;
    for (int i = 0; i < n1; i++) {
        used.assign(n1, false);
        ans += dfs(i);
    }
    cout << ans << '\n';
    for (int i = 0; i < n2; i++) {
        if (p[i] != -1) {
            cout << p[i] + 1 << ' ' << i + 1 << '\n';
        }
    }
}