#include <bits/stdc++.h>

using namespace std;

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

const int nmax = 20005, inf = 1e9;
int n, m, e, match[nmax], cuplaj, dist[nmax];
vector <int> G[nmax];

bool bfs(){
    queue <int> coada;
    for (int i = 1; i <= n; ++i){
        dist[i] = inf;
        if (match[i] == 0){
            coada.push(i);
            dist[i] = 0;
        }
    }
    dist[0] = inf;
    while (!coada.empty()){
        int nod = coada.front();
        coada.pop();
        if (nod != 0){
            for (auto it : G[nod]){
                if (dist[match[it]] == inf){
                    dist[match[it]] = 1 + dist[nod];
                    coada.push(match[it]);
                }
            }
        }
    }
    return dist[0] != inf;
}

bool dfs(int nod){
    if (nod){
        for (auto it : G[nod]){
            if (1 + dist[nod] == dist[match[it]] && dfs(match[it])){
                match[nod] = it;
                match[it] = nod;
                return true;
            }
        }
        return false;
    }
    return true;
}

int main(){
    fin >> n >> m >> e;
    for (int i = 1; i <= e; ++i){
        int x, y;
        fin >> x >> y;
        G[x].push_back(y + n);
        G[y + n].push_back(x);
    }
    while (bfs()){
        for (int i = 1; i <= n; ++i){
            if (match[i] == 0 && dfs(i)){
                ++cuplaj;
            }
        }
    }
    fout << cuplaj << "\n";
    for (int i = 1; i <= n; ++i){
        if (match[i])
            fout << i << " " << match[i] - n << "\n";
    }
    fin.close();
    fout.close();
    return 0;
}