/*Cuplaj maxim in graf bipartit*/ 
#include<iostream>
#include<vector>
#include<fstream>
using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");

#define NMAX 10001
int n,m,e;
vector<int> G[2*NMAX], st(2*NMAX,0), dr(2*NMAX,0);
vector<bool> uz(2*NMAX, 0);

bool cupleaza(int worker) {
    if (uz[worker]) return 0; //nu poate fi deranjat
    uz[worker] = 1;
    for (auto job: G[worker]) {
        if (!dr[job] /*nu este cuplat*/ || 
            cupleaza(dr[job] /*perechea lui poate fi recuplata*/)) {
            dr[job] = worker;
            st[worker] = job;
            return 1;
        }
    }
    return 0;
}

int main() {
    fin >> n >> m >> e;
    while (e--) {
        int worker,job; fin >> worker >> job;
        job+=n;
        G[worker].push_back(job);
        G[job].push_back(worker);
    }

    int nrperechi = 0;
    for (int worker = 1; worker<=n; worker++) {
        if (st[worker]) continue; //este cuplat
        if (cupleaza(worker)) { //incerc sa cuplez fara sa deranjez alte noduri
            nrperechi++;
        } else {
            uz.assign(2*NMAX, 0);
            if (cupleaza(worker)) { //incerc sa reorganizez
                nrperechi++;
            }
        }
    }

    fout << nrperechi << '\n';
    for (int i = 1; i<=n; i++) {
        if (st[i]) {
            fout << i << ' ' << st[i]-n << '\n';
        }
    }
    return 0;
}