#include <stdio.h>
# include <vector>
# include <string.h>
using namespace std;
int i,m,n,k,st[100010],dr[100010],nr,x,y;
bool use[100010],ok;

vector <int> v[100010];
bool cupleaza(int nod)
{
    int i;
    bool ok;
    if (use[nod]==true) return 0;
    use[nod]=true;
    for (i=1; i<=m; i++)
    {
        ok=false;
        for (int j=0; j<v[nod].size(); j++)
            if (v[nod][j]==i) {ok=true; break;}
        if (ok==true)
        {
            if (!dr[i] || cupleaza(dr[i]))
            {
                st[nod]=i;
                dr[i]=nod;
                return 1;
            }
        }
        else continue;
    }
    return 0;
}
void cuplaj()
{
    int i;
    for (i=1; i<=n; i++)
    {
        if (st[i]) continue;
        if (cupleaza(i)) nr++;
        else
        {
            memset(use,false,sizeof(use));
            if (cupleaza(i)) nr++;
        }
    }
}
int main()
{
    freopen("cuplaj.in","r",stdin);
    freopen("cuplaj.out","w",stdout);
    scanf("%d %d %d\n",&n,&m,&k);
    for (i=1; i<=k; i++)
    {
        scanf("%d %d\n",&x,&y);
        v[x].push_back(y);
        //v[y].push_back(x);
    }
    nr=0;

    cuplaj();

    printf("%d\n",nr);
    for (i=1; i<=n; i++)
         if (st[i])
             printf("%d %d\n",i,st[i]);
    return 0;
}