#include<fstream>
#include<cstdio>
#include<vector>
#include<cstring>
#define DIM 10015
using namespace std;
int n, m, e, i, j, sol, ok, x, y;
vector<int> v[DIM];
int viz[DIM];
int a[DIM], b[DIM];
FILE * fin = fopen("cuplaj.in", "r");
FILE * fout = fopen("cuplaj.out", "w");
int cupleaza(int nod){
    if(viz[nod] == 1){
        return 0;
    }
    viz[nod] = 1;
    for(int i = 0; i < v[nod].size(); i++){
        int vecin = v[nod][i];
        if(b[vecin] == 0){
            a[nod] = vecin;
            b[vecin] = nod;
            sol++;
            return 1;
        }
    }

    for(int i = 0; i < v[nod].size(); i++){
        int vecin = v[nod][i];
        if(cupleaza(b[vecin])){
            a[nod] = vecin;
            b[vecin] = nod;
            return 1;
        }
    }
    return 0;
}
int main(){
    fscanf(fin, "%d%d%d", &n, &m, &e);
    for(i = 1; i <= e; i++){
        fscanf(fin, "%d%d", &x, &y);
        v[x].push_back(y);
    }
    do{
        ok = 0;
        memset(viz, 0, sizeof(viz));
        for(i = 1; i <= n; i++){
            if(a[i] == 0){
                ok = ok || cupleaza(i);
            }
        }
    }while(ok == 1);

    fprintf(fout,"%d\n", sol);
    for(i = 1; i <= n; i++){
        if(a[i] != 0){
            fprintf(fout, "%d %d\n", i, a[i]);
        }
    }
    return 0;
}