#include <bits/stdc++.h>
using namespace std;
ifstream f("cuplaj.in");
ofstream g("cuplaj.out");
vector <int> v[10009];
int st[10009], dr[10009], tried[10009];
int n, m, q, ans;
bool augment (int nod)
{
    if (tried[nod])
        return 0;
    tried[nod]=1;
    //cout << nod << ' ';
    for (auto y:v[nod])
    {
        if (!st[y])
        {
            dr[nod]=y;
            st[y]=nod;
            ans++;
            return 1;
        }
    }
    for (auto y:v[nod])
    {
        if (augment (st[y]))
        {
            st[y]=nod;
            dr[nod]=y;
            return 1;
        }
    }
    return 0;
}
void cuplaj ()
{
    bool ok=1;
    while (ok)
    {
        ok=0;
        for (int i=1; i<=n; i++)
            tried[i]=0;
        for (int i=1; i<=n; i++)
            if (!dr[i]) ok|=augment(i);
    }
}
signed main ()
{
    f >> n >> m >> q;
    while (q--)
    {
        int a, b;
        f >> a >> b;
        v[a].push_back(b);
    }
    cuplaj ();
    g << ans<<'\n';
    for (int i=1; i<=n; i++)
    {
        if (dr[i]) g << i << ' ' << dr[i] << '\n';
    }
}