#include <fstream>
#include <vector>

using namespace std;

ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");

const int DMAX = 10000;

int N, M, E;

vector <int> g[DMAX + 5];

bool d[DMAX + 5];

int matches;
int l[DMAX + 5], r[DMAX + 5];

void Read()
{
    fin >> N >> M >> E;

    for(int i = 1; i <= E; i++)
        {
            int x, y;
            fin >> x >> y;

            g[x].push_back(y);
        }
}

bool PairUp(int node)
{
    if(d[node] == 1)
        return false;

    d[node] = 1;

    ///nod neimperecheat adiacent
    for(auto it : g[node])
        if(!r[it])
            {
                ++matches;

                l[node] = it;
                r[it] = node;

                return true;
            }

    ///augmenting path
    for(auto it : g[node])
        if(PairUp(r[it]))
            {
                l[node] = it;
                r[it] = node;

                return true;
            }

    return false;
}

void Solve()
{
    bool ok;

    do
    {
        for(int i = 1; i <= N; i++)
            d[i] = 0;

        ok = false;

        for(int i = 1; i <= N; i++)
            if(!l[i]) ///nod neimperecheat
                ok |= PairUp(i);
    }
    while(ok);
}

int main()
{
    Read();

    Solve();

    fout << matches << '\n';

    for(int i = 1; i <= N; i++)
        if(l[i])
        fout << i << ' ' << l[i] << '\n';

    return 0;
}