#include <iostream>
#include <fstream>
#include <vector>
#include <bitset>


typedef std::vector<int>::iterator iter;


const int MAXN = 10005;
std::ifstream f("cuplaj.in");
std::ofstream g("cuplaj.out");
std::vector<int> G[MAXN]; int n, m, e;
std::bitset<MAXN> viz;
int left[MAXN], right[MAXN];


bool match(int node)
{
    if (viz[node] == true) {
        return false;
    }
    viz[node] = true;

    for (iter it = G[node].begin(); it != G[node].end(); it++) {
        if (right[*it] == 0) {
            right[*it] = node;
            left[node] = *it;
            return true;
        }
    }
    for (iter it = G[node].begin(); it != G[node].end(); it++) {
        if (match(right[*it])) {
            right[*it] = node;
            left[node] = *it;
            return true;
        }
    }
    return false;
}


int main()
{
    f >> n >> m >> e;
    for (int i = 1, x, y; i <= e; i++) {
        f >> x >> y;
        G[x].push_back(y);
    }


    bool ok = true;
    while (ok) {
        ok = false;
        viz.reset();

        for (int i = 1; i <= n; i++) {
            if (left[i] == 0) {
                ok |= match(i);
            }
        }
    }


    int sol = 0;
    for (int i = 1; i <= n; i++) {
        if (left[i] != 0) {
            sol++;
        }
    }
    g << sol << '\n';
    for (int i = 1; i <= n; i++) {
        if (left[i] != 0) {
            g << i << ' ' << left[i] << '\n';
        }
    }


    f.close();
    g.close();
    return 0;
}