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

using namespace std;

ifstream f ("cuplaj.in");
ofstream g ("cuplaj.out");

const int NMAX = 10000 + 1;

int n, m, e;
vector <int> graf[NMAX];
bool vizitat[NMAX];
int A[NMAX], B[NMAX];

void citeste() {
    f >> n >> m >> e;
    int a, b;
    for (int i = 1; i <= e; i++) {
        f >> a >> b;
        graf[a].push_back(b);
    }
}

bool DFS(int nod) {
    if (vizitat[nod]) return false;
    vizitat[nod] = true;

    int fiu, l = graf[nod].size();
    for (int i = 0; i < l; i++) {
        fiu = graf[nod][i];
        if (!A[fiu] || DFS(A[fiu])) {
            A[fiu] = nod;
            B[nod] = fiu;
            return true;
        }
    }
    return false;
}
void cuplaj() {
    bool ok = true;
    while (ok) {
        ok = false;
        for (int i = 1; i <= n; i++) vizitat[i] = false;
        for (int i = 1; i <= n; i++)
            if (!B[i]) {
                if (DFS(i)) ok = true;
            }
    }
}

void scrie() {
    int nr = 0;
    for (int i = 1; i <= n; i++) if (B[i]) nr++;
    g << nr << '\n';
    for (int i = 1; i <= n; i++)
        if (B[i]) g << i << ' ' << B[i] << '\n';
}

int main() {
    citeste();
    cuplaj();
    scrie();
    return 0;
}