#include <iostream>
#include <fstream>
#include <stdio.h>
#include <string.h>
#include <vector>
#define LMAX 100101

using namespace std;

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

int n,m,l;//date de intrare
int viz[LMAX];
vector<int> G[LMAX];
int cuplaj1[LMAX];
int cuplaj2[LMAX];
int nr;

 int leaga(int nod){
    int x;
    if (viz[nod] == 1){//nod deja legat
        return 0;
    }
    viz[nod]=1;//vizitam
    int nrVec = G[nod].size() - 1;
    for (int i = 0; i <= nrVec ;++i){
        x = G[nod][i];
        if (cuplaj1[x] == 0){//nod care nu e legat
            cuplaj2[nod] = 1;// nod este legat de vecinul sau
            cuplaj1[x] = nod;//legam x de nod
            return 1;
        }
    }
    for (int i = 0; i <= nrVec; ++i){
        x = G[nod][i];
        if (cuplaj1[x] != nod && leaga(cuplaj1[x])){
            cuplaj2[nod]=1;
            cuplaj1[x]=nod;
            return 1;
        }
    }

    return 0;
}

int main(){
    in >> n >> m >> l;
    for (int i = 1; i <= l; ++i){
        int a, b;
        in >> a >> b;
        G[a].push_back(b);
    }
    bool ok = false;
    while(ok == false){
        memset(viz,0,sizeof(viz));
        ok=true;
        for (int i = 1; i <= n; ++i){
            if (cuplaj2[i]==0 && leaga(i)){
                ok = false;
                nr++;
            }
        }
    }
    out << nr << '\n';
    for (int i = 1; i <= m; ++i){
          if (cuplaj1[i]!=0){
              out << cuplaj1[i] << ' ' << i << '\n';
          }
    }
    return 0;
}