#include <stdio.h>

#define DIM 10005

struct nod {int x;
            nod *urm;} *lst[DIM];
int l[DIM],r[DIM],viz[DIM];
int n,m,e,cuplaj;

void add (nod *&q,int val)
{
    nod *p=new nod;

    p->x=val;
    p->urm=q;
    q=p;
}

void read ()
{
    int i,x,y;

    scanf ("%d%d%d",&n,&m,&e);
    for (i=1; i<=e; ++i)
    {
        scanf ("%d%d",&x,&y);
        add (lst[x],y);
    }
}

int pairup (int start)
{
    nod *p;

    if (viz[start])
        return 0;
    viz[start]=1;
    for (p=lst[start]; p; p=p->urm)
        if (!r[p->x])
        {
            r[p->x]=start;
            l[start]=p->x;
            return 1;
        }
    for (p=lst[start]; p; p=p->urm)
        if (pairup (r[p->x]))
        {
            l[start]=p->x;
            r[p->x]=start;
            return 1;
        }
    return 0;
}

void solve ()
{
    int i,ok;

    do
    {
        ok=0;
        for (i=0; i<DIM; ++i)
            viz[i]=0;
        for (i=1; i<=n; ++i)
            if (!l[i] && pairup (i))
            {
                ++cuplaj;
                ok=1;
            }

    }
    while (ok);
}

void print ()
{
    int i;

    printf ("%d\n",cuplaj);
    for (i=1; i<=n; ++i)
        if (l[i])
            printf ("%d %d\n",i,l[i]);
}

int main ()
{
    freopen ("cuplaj.in","r",stdin);
    freopen ("cuplaj.out","w",stdout);

    read ();
    solve ();
    print ();

    return 0;
}