//ALEX ENACHE

#include <vector>
#include <algorithm>
#include <queue>
#include <map>
#include <set>
#include <unordered_map>
#include <time.h>
#include <iomanip>
#include <deque>
#include <math.h>
#include <assert.h>
#include <stack>
#include <bitset>
#include <random>
#include <chrono>

using namespace std;

const double PI = acos(-1);
const double eps = 1e-6;

inline long long lgput(long long a , long long b , long long mod) {
    long long ret = 1;
    while( b ){
        if(b & 1) ret = (ret * a) % mod;
        a = (a * a) % mod;
        b >>= 1;
    }

    return (ret%mod);
}

inline long long inv(long long x , long long MOD) {
    return lgput(x, MOD - 2, MOD);
}

inline bool exist (double nr){
    return (nr < -eps) || (nr > eps);
}

long long big_rand(){
    return rand () * RAND_MAX + rand();
}

//-----------------------------------------------------------------

//#include <iostream>
#include <fstream>
ifstream cin ("cuplaj.in");ofstream cout ("cuplaj.out");

vector < int > gr[10100];
int ans[10100];
int used[10100];
int cup[10100];

bool cuplaj (int nod){
    used[nod] = 1;
    for (auto &x : gr[nod]){
        if (!ans[x]){
            ans[x] = nod;
            return 1;
        }
    }
    for (auto &x : gr[nod]){
        if (!used[ans[x]] && cuplaj(ans[x])){
            ans[x] = nod;
            return 1;
        }
    }
    return 0;
}

vector < pair < int , int > > v;

int main() {

    //freopen("input", "r", stdin);freopen("output", "w", stdout);

    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    cout << setprecision(10) << fixed;
    mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
    srand(time(nullptr));

    int n , m , e;
    cin>>n>>m>>e;

    for (int i=1; i<=e; i++){
        int a , b;
        cin>>a>>b;
        gr[a].push_back(b);
    }

    int c = 1;
    while (c){
        c = 0;
        for (int i=1; i<=n; i++){
            used[i] = 0;
        }
        for (int i=1; i<=n; i++){
            if (!used[i] && !cup[i]){
                int now = cuplaj(i);
                cup[i] = now;
                c |= now;
            }
        }
    }

    for (int i=1; i<=m; i++){
        if (ans[i]){
            v.push_back({ans[i] , i});
        }
    }

    cout<<v.size()<<'\n';

    for (auto &x : v){
        cout<<x.first<<" "<<x.second<<'\n';
    }


    return 0;
}