#include<fstream>
#include<vector>
#include<queue>
#include<climits>

using namespace std;

ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
int n, m, x, y, z, s, t, l, r;
int capacitate[5001][5001];
vector<vector<int>> graf;
int tata[5001];

bool bfs(){
    queue<int> q;
    int vizitat[n+1];

    for(int i=1 ; i<=n; i++)
        vizitat[i] = 0;

    q.push(s);
    vizitat[s] = 1;
    tata[s] = -1;
    while(!q.empty()){
        int u = q.front();
        q.pop();
        for(auto v: graf[u]){
            if(vizitat[v] == 0 && capacitate[u][v] != 0){
                tata[v] = u;
                if(v == t)
                    return true;

                vizitat[v] = 1;
                q.push(v);
            }
        }
    }

    return false;
}

int flux_maxim(){
    int fluxmax = 0;
    while (bfs()){
        int u, v = t, flux = INT_MAX;

        while(v!=s){
            u = tata[v];

            if(capacitate[u][v] < flux)
                flux = capacitate[u][v];

            v = tata[v];
        }

        v = t;

        while(v != s){
            u = tata[v];
            capacitate[u][v] -= flux;
            capacitate[v][u] += flux;
            v = tata[v];
        }

        fluxmax += flux;
    }

    return fluxmax;

}

int main() {
    fin>>l>>r>>m;
    n = l+r+2;
    s = 0;
    t = n-1;
    graf.resize(n);

    for(int i=1; i<=m; i++){
        fin>>x>>y;
        graf[x].push_back(y+l);
        graf[y+l].push_back(x);
        capacitate[x][y+l] = 1;
    }

    for(int i=1; i<=l; i++){
        graf[s].push_back(i);
        graf[i].push_back(s);
        capacitate[s][i] = 1;
    }

    for(int i= l+1; i<= n-1; i++){
        graf[i].push_back(t);
        graf[t].push_back(i);
        capacitate[i][t] = 1;
    }

    fout<<flux_maxim()<<"\n";

    for(int i=1; i <= l; i++){
        for(auto v: graf[i]){
            if(capacitate[i][v] == 0 && v != s && v != t)
                fout<<i<<" "<<v-l<<"\n";
        }
    }
}