#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

#pragma GCC optimize ("O1")
#pragma GCC optimize ("O2")
#pragma GCC optimize ("O3")
#pragma GCC optimize ("Ofast")
#pragma GCC optimize ("unroll-loops")
#pragma GCC target ("avx2")

using namespace std;
using namespace __gnu_pbds;

#define ordered_set tree <long long, null_type, less<long long>, rb_tree_tag, tree_order_statistics_node_update>
#define lsb(x)(x & (-x))

const int max_size = 1e4 + 20;

int viz[max_size], l[max_size], r[max_size];
vector <int> mc[max_size];

bool pairup (int nod)
{
    if (viz[nod] == 1)
    {
        return false;
    }
    viz[nod] = 1;
    for (auto f : mc[nod])
    {
        if (r[f] == 0)
        {
            l[nod] = f;
            r[f] = nod;
            return true;
        }
    }
    for (auto f : mc[nod])
    {
        if (pairup(r[f]))
        {
            l[nod] = f;
            r[f] = nod;
            return true;
        }
    }
    return false;
}

void solve ()
{
    int n, m, q;
    cin >> n >> m >> q;
    while (q--)
    {
        int x, y;
        cin >> x >> y;
        mc[x].push_back(y);
    }
    while (1)
    {
        bool ok = 0;
        for (int i = 1; i <= n; i++)
        {
            viz[i] = 0;
        }
        for (int i = 1; i <= n; i++)
        {
            if (l[i] == 0)
            {
                ok |= pairup(i);
            }
        }
        if (!ok)
        {
            break;
        }
    }
    vector <pair <int, int>> v;
    for (int i = 1; i <= n; i++)
    {
        if (l[i] != 0)
        {
            v.push_back({i, l[i]});
        }
    }
    cout << v.size() << '\n';
    for (auto f : v)
    {
        cout << f.first << " " << f.second << '\n';
    }
    cout << '\n';
}

signed main ()
{
#ifdef LOCAL
    freopen("test.in", "r", stdin);
    freopen("test.out", "w", stdout);
#else
    freopen("cuplaj.in", "r", stdin);
    freopen("cuplaj.out", "w", stdout);
#endif // LOCAL
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    long long tt;
    //cin >> tt;
    tt = 1;
    while (tt--)
    {
        solve();
    }
    return 0;
}