#include <bits/stdc++.h>
using namespace std;

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)
{
    for (auto vec: G[nod])
    {
        if (viz[vec]) /// blocat
            continue;

        if (!inv[vec]) /// nu e atribuit
        {
            v[nod] = vec;
            inv[vec] = nod;
            viz[vec] = 1;
            return 1;
        }
        else /// e atribuit
        {
            int x = inv[vec];
            v[nod] = vec;
            inv[vec] = nod;
            viz[vec] = 1; /// blocam
            if (pun(x)) /// a mers
            {
                return 1;
            }
            else /// n-a mers
            {
                v[x] = vec;
                inv[vec] = x;
                v[nod] = 0;
            }
        }
    }
    return 0;
}

int main()
{
    FILE *fi, *fo;
    fi = fopen("cuplaj.in", "r");
    fo = fopen("cuplaj.out", "w");

    fscanf(fi, "%d%d%d", &n, &m, &e);
    for (int i = 1; i <= e; i++)
    {
        int u, v;
        fscanf(fi, "%d%d", &u, &v);
        G[u].push_back(v);
    }

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

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

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

    return 0;
}