#include <cstdio>
#include <cstdlib>
#define DIM 20005

struct muchie
{
    int x, capflux;
    muchie *next;
};

muchie *G[DIM];

int n, m , nr_cuplaj, nrM, tata[DIM], cuplaj;

void addMuchie(int i, int j, int cf)
{

    muchie *t = new muchie;
    t -> x = j;
    t -> capflux = cf;
    t -> next = G[i];
    G[i] = t;
}

void Read()
{

    FILE *f = fopen("cuplaj.in", "r");

    fscanf(f, "%d%d%d", &n, &m, &nrM);

    for (int i = 1, x, y; i <= nrM; ++i)
    {
        fscanf(f, "%d%d", &x, &y);
        addMuchie(x, y + n, 1);
        addMuchie(y + n, x, 0);
    }
    
    for (int i = 1; i <= n; ++i)
        addMuchie(0, i, 1),
        addMuchie(i, 0, 0);
    
    for (int i = n + 1; i <= n + m; ++i)
        addMuchie(i, n + m + 1, 1),
        addMuchie(n + m + 1, i, 0);
      
    fclose(f);

}

int BFS(int s, int d)
{
    int coada[DIM], st, dr, k, i;
    st = dr = 1;
    for (i = 0; i <= n + m + 1; ++i)
        tata[i] = -2;
    
    coada[1]=s, tata[s] = -1;
    while (st <= dr)
    {
        k = coada[st++];
        for (muchie *t = G[k]; t; t = t->next)
        {
                i = t -> x;
                if (tata[i] == -2 && t->capflux)
                        coada[++dr] = i, tata[i] = k;
        }
        if (k == d)
                return 1;
    }
        
    return 0;
}
muchie * adresa_muchie (int i, int j)
{
    for (muchie *p = G[i]; p ; p = p -> next)
        if (p -> x == j)
                return p;
    
    printf ("baaaaaa\n");
    return NULL;
}


void e_k()
{
    int k, i, dcur, j;
    muchie *p;
    while (BFS(0, n+m+1)) 
    {
        for (j = n + 1; j <= n+m; ++j)
        {
                p = adresa_muchie(j, n+m+1);
                if (p->capflux == 0 || tata[j] == -2)
                       continue;
                k = n+m+1;                
                tata[k] = j;
                dcur = 4;
                while (tata[k] != -1)
                {
                        p = adresa_muchie(tata[k], k);
                        if (p->capflux < dcur)
                             dcur = p->capflux;
                        k = tata[k];                                                                       
                }
                
                cuplaj += dcur;
                k = n+m+1;
                while (tata[k] != -1)
                {
                        p = adresa_muchie(tata[k], k);
                        p->capflux -= dcur;
                        p = adresa_muchie(k, tata[k]);
                        p->capflux += dcur;
                        k = tata[k];
                } 
                        

        }
    }
}

int main()
{
    Read();
    e_k();
    FILE *f = fopen("cuplaj.out", "w");
    
    fprintf (f, "%d\n", cuplaj);
    for (int i = 1, gasit = 0; i <= n; ++i)
    {
        gasit = 0;
        for(muchie *t = G[i]; t && !gasit; t = t -> next)
                if (t->capflux == 0 && t->x > n)
                        fprintf (f, "%d %d\n", i, t->x - n), gasit = 1;
    }
    fclose(f);
    
    return 0;
}