#include <bits/stdc++.h>
using namespace std;

#define nmax 10005

int n, m, e, x, y, i;
int u[nmax], l[nmax], r[nmax];
vector <int> G[nmax];
int ok;

ifstream f("cuplaj.in");
ofstream g("cuplaj.out");

int pairup(int nod)
{
    if (u[nod])
        return 0;
    u[nod] = 1;

    for (auto &it : G[nod])
        if (!r[it])
        {
            l[nod] = it;
            r[it] = nod;
            return 1;
        }

    for (auto &it : G[nod])
        if (pairup(r[it]))
        {
            l[nod] = it;
            r[it] = nod;
            return 1;
        }

    return 0;
}

int main()
{
    f>>n>>m>>e;

    for (i=1;i<=e;i++)
    {
        f>>x>>y;
        G[x].push_back(y);
    }

    int cuplaj = 0;

    ok = 1;
    while (ok)
    {
        ok = 0;
        memset(u, 0, sizeof(u));
        for (i=1;i<=n;i++)
            if(!l[i])
                ok |= pairup(i);
    }

    for (i=1;i<=n;i++)
        if (l[i] > 0)
            cuplaj++;

    g<<cuplaj<<"\n";
    for (i=1;i<=n;i++)
        if (l[i] > 0)
            g<<i<<" "<<l[i]<<"\n";

    f.close();
    g.close();
    return 0;
}