#include <bits/stdc++.h>
using namespace std;
ifstream fi("cuplaj.in");
ofstream fo("cuplaj.out");

const int NMAX = 1e4 + 5;

vector <int> G[NMAX];
int n, m, e;
int v[NMAX], inv[NMAX];
bool viz[NMAX];

bool pun(int nod)
{
    if (viz[nod])
        return 0;
    viz[nod] = 1;

    for (auto vec: G[nod])
    {
        if (!inv[vec]) /// nu e atribuit
        {
            v[nod] = vec;
            inv[vec] = nod;
            return 1;
        }
        else /// e atribuit
        {
            int x = inv[vec];
            if (pun(x)) /// a mers
            {
                v[nod] = vec;
                inv[vec] = nod;
                return 1;
            }
        }
    }
    return 0;
}

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

    bool gt = 0;
    while (!gt)
    {
        gt = 1;
        memset(viz, 0, sizeof(viz));
        for (int i = 1; i <= n; i++)
            if (!v[i])
                if (pun(i))
                    gt = 0;
    }

    int cnt = 0;
    for (int i = 1; i <= n; i++)
        if (v[i])
            cnt++;

    fo << cnt << "\n";
    for (int i = 1; i <= n; i++)
        if (v[i])
            fo << i << " " << v[i] << "\n";

    return 0;
}