#include <fstream>
#include <vector>
#include <cstring>
#define DIM 10005
using namespace std;

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

vector <int> node[DIM];

int l_match[DIM], r_match[DIM], vis[DIM], l, r, edges, sol;

bool cupleaza(int vertex){
    int neigh;
    if(vis[vertex]) return false;
    vis[vertex]=1;
    for(int i=0; i<node[vertex].size(); ++i){
        neigh=node[vertex][i];
        if(!r_match[neigh]){
            l_match[vertex]=neigh;
            r_match[neigh]=vertex;
            return true;
        }
    }
    for(int i=0; i<node[vertex].size(); ++i){
        if(cupleaza(r_match[node[vertex][i]])){
            neigh=node[vertex][i];
            l_match[vertex]=neigh;
            r_match[neigh]=vertex;
            return true;
        }
    }
    return false;
}

int main()
{
    int a, b;
    short temp=1;
    in>>l>>r>>edges;
    while(edges--){
        in>>a>>b;
        node[a].push_back(b);
    }
    while(temp){
        memset(vis, 0, sizeof(vis));
        temp=0;
        for(int i=1; i<=l; ++i){
            if(!l_match[i]&&cupleaza(i)){
                sol++; temp=1;
            }
        }
    }
    out<<sol<<"\n";
    for(int i=1; i<=l; ++i){
        if(l_match[i])
            out<<i<<" "<<l_match[i]<<"\n";
    }
    return 0;
}