#include <bits/stdc++.h>

using namespace std;

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

#define NMAX 10005

int n, m, e, x, y, viz[NMAX], dr[NMAX], st[NMAX];
vector<int> v[NMAX];
int pairup(int nod)
{
    if (viz[nod] == 1)
        return 0;
    viz[nod] = 1;
    for (int i=0; i<v[nod].size(); i++)
    {
        int vec = v[nod][i];
        if (!st[vec] || pairup(st[vec]))
        {
            st[vec] = nod;
            dr[nod] = vec;
            return 1;
        }
    }
    return 0;
}
int main()
{
    f >> n >> m >> e;
    for (int i=1; i<=e; i++)
    {
        f >> x >> y;
        v[x].push_back(y);
    }
    bool ok = true;
    while(ok)
    {
        memset(viz, 0, sizeof(viz));
        ok = false;
        for (int i=1; i<=n; i++)
        {
            if (!dr[i] && pairup(i))
                ok = true;
        }
    }
    int ans = 0;
    for (int i=1; i<=n; i++)
    {
        if (dr[i])
            ans ++;
    }
    g << ans << '\n';
    for (int i=1; i<=n; i++)
    {
        if (dr[i])
        {
            g << i << ' ' << dr[i] << '\n';
        }
    }
    return 0;
}