#include <fstream>
#include <vector>

using namespace std;

ifstream cin("cuplaj.in");
ofstream cout("cuplaj.out");

const int NMAX = 10000;

int N, M, E;
vector <int> g[NMAX + 2];

bool d[NMAX + 2];
int l[NMAX + 2], r[NMAX + 2];

int matches;

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

    d[node] = true;

    for(auto it : g[node])
        if(!r[it])
        {
            ++matches;
            l[node] = it;
            r[it] = node;

            return true;
        }

    for(auto it : g[node])
        if(PairUp(r[it]))
            {
                l[node] = it;
                r[it] = node;
                return true;
            }

    return false;
}

void Solve()
{
    bool ok;

    do
    {
        ok = false;

        for(int i = 1; i <= N; i++)
            d[i] = false;

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

int main()
{
    cin >> N >> M >> E;

    for(int i = 1; i <= E; i++)
        {
            int x, y;
            cin >> x >> y;
            g[x].push_back(y);
        }

    Solve();

    cout << matches << '\n';

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

    return 0;
}