#include <algorithm>
#include <iostream>
#include <fstream>
#include <climits>
#include <vector>
#include <stack>
#include <cmath>
// #include <bits/stdc++.h>
#define in  fin
#define out fout

using namespace std;

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

vector<int> g[100001];
int cuplaj[100001]; // cuplaj[i] = cu cine e cuplat i
bool mr[100001];

bool pair_up(int nod){
    // cout << "nod = " << nod << endl;
    if(mr[nod]) return 0;
    mr[nod] = 1;
    // for(const int &cop : g[nod]){
    //     if(!cuplaj[cop]){
    //         cuplaj[cop] = nod;
    //         cuplaj[nod] = cop;
    //         return 1;
    //     }
    // }

    for(const int &cop : g[nod]){
        if(!cuplaj[cop] || pair_up( cuplaj[cop] )){
            cuplaj[cop] = nod;
            cuplaj[nod] = cop;
            return 1;
        }
    }
    return 0;
}

signed main(){
    ios_base::sync_with_stdio(false);
    in.tie(NULL);

    int n, m, E; in >> n >> m >> E;
    for(int ii = 0; ii < E; ii++){
        int a, b; in >> a >> b;
        // sa fie in stange 1, 2, ... , n si la dreapta n + 1, n + 2, ... n + m
        g[a].push_back(b + n);
    } 

    bool mai_bine = 1;
    int sol = 0;
    while(mai_bine){
        mai_bine = 0;
        for(int i = 1; i <= n; i++) mr[i] = 0;
        for(int i = 1; i <= n; i++){
            if(!cuplaj[i] && pair_up(i)){
                mai_bine = 1;
                sol++;
            }
        }
    }

    out << sol << '\n';
    for(int i = 1; i <= n; i++){
        if(cuplaj[i]){
            out << i << " " << cuplaj[i] - n << '\n';
        }
    }

    return 0;
}