#include <algorithm>
#include <iostream>
#include <fstream>
#include <climits>
#include <vector>
#include <deque>
#include <queue>
#include <stack>
#include <map>
#include <set>

#include <iomanip>
#include <cassert>

#include <random>
#include <chrono>

// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")

using ull = unsigned long long;
using ll = long long;

//#define int __int128
#define int ll
#define pii pair <int, int>
#define all(a) (a).begin(), (a).end()
#define fr first
#define sc second
#define pb push_back
#define lb lower_bound
#define ub upper_bound

#define vt vector
#define FOR(a, b) for(int i = (a); i <= (b); i++)
#define FORr(a, b) for(int i = (a); i >= (b); i--)
#define sz(x) (int)(x).size()

#define YES cout << "YES\n"
#define NO cout << "NO\n"

using namespace std;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int rangerng(int l, int r){
    return uniform_int_distribution<>(l, r)(rng);
}

string filename = "cuplaj";
ifstream fin(filename + ".in");
ofstream fout(filename + ".out");

////////////////////////////////////////////////////////////////////////////////////

const int NMAX = 1e4;

vt <int> adj[NMAX + 1];
int l[NMAX + 1];
int r[NMAX + 1];

bool viz[NMAX + 1];

bool pair_up(int node){
    if(viz[node]){
        return 0;
    }
    viz[node] = 1;

    for(int vec : adj[node]){
        if(r[vec] == 0){
            l[node] = vec;
            r[vec] = node;
            return 1;
        }
    }

    for(int vec : adj[node]){
        if(pair_up(r[vec])){
            l[node] = vec;
            r[vec] = node;
            return 1;
        }
    }

    return 0;
}

void solve(){
    int n, m, E;
    fin >> n >> m >> E;

    for(int i = 1; i <= E; i++){
        int a, b;
        fin >> a >> b;
        adj[a].pb(b);
    }

    while(1){
        for(int i = 1; i <= n; i++){
            viz[i] = 0;
        }

        bool ok = 0;
        for(int i = 1; i <= n; i++){
            if(l[i] == 0){
                ok |= pair_up(i);
            }
        }

        if(!ok){
            break;
        }
    }

    int ans = 0;
    vt <pii> e;
    for(int i = 1; i <= n; i++){
        if(l[i] != 0){
            ans++;
            e.pb({i, l[i]});
        }
    }

    fout << ans << '\n';
    for(pii x : e){
        fout << x.fr << ' ' << x.sc << '\n';
    }
}   


signed main(){

    ios_base::sync_with_stdio(false);
    cin.tie(0);

    int T;
    //cin >> T;

    T = 1;

    while(T--){
        solve();
    }

    return 0;
}

/*
*/