#include <iostream>
#include <fstream>
#include <algorithm>
#include <cmath>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <queue>
#include <stack>
#include <deque>
#include <iomanip>
#include <vector>
#include <cassert>

#pragma GCC optimize("O3")

#define fi first
#define se second
#define pb push_back
#define pf push_front

using namespace std;

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

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const ll Nmax=1e4+5, inf=1e9+5;

int n, m, e;
vector<int> ltor[Nmax];
int pl[Nmax], pr[Nmax];
bool vis[Nmax];

vector<pii> cuplaj;

bool augment(int nod){ // nod stang
    for (auto it:ltor[nod])
        if (!vis[it]){
            vis[it]=1;
            if (!pr[it] || augment(pr[it])){
                pl[nod]=it;
                pr[it]=nod;
                return 1;
            }
        }
    return 0;
}

int main()
{
    fin>>n>>m>>e;
    int a, b;
    for (int i=0; i<e; i++){
        fin>>a>>b;
        ltor[a].pb(b);
    }   

    bool ok=1;
    while (ok){
        ok=0;
        for (int i=1; i<=n; i++)
            vis[i]=0;

        for (int i=1; i<=n; i++)
            if (!pl[i] && augment(i))
                ok=1;
    }

    for (int i=1; i<=n; i++)
        if (pl[i])
            cuplaj.pb({i, pl[i]});

    fout<<cuplaj.size()<<'\n';
    for (auto it:cuplaj)
        fout<<it.fi<<' '<<it.se<<'\n';

    return 0;
}