#include <fstream>
#include <vector>

bool visit(std::vector<int> *myG, int *l, int *r, bool *seen, int x)
{
    if (seen[x])
    {
        return false;
    }
    seen[x] = true;
    for (int i = 0; i < (int)myG[x].size(); i++)
    {
        if (r[myG[x][i]] < 0 || visit(myG, l, r, seen, r[myG[x][i]]))
        {
            l[x] = myG[x][i];
            r[myG[x][i]] = x;
            return true;
        }
    }
    return false;
}

int main()
{
    std::ifstream in("cuplaj.in");
    std::ofstream out("cuplaj.out");
    int nV, nM, nE;
    in >> nV >> nM >> nE;
    std::vector<int> *myG = new std::vector<int>[nV + 1];
    bool *seen = new bool[nV + 1];
    int *l = new int[nV + 1], *r = new int[nM + 1];
    for (int i = 0; i <= nV; i++)
    {
        l[i] = -1;
    }
    for (int i = 0; i <= nM; i++)
    {
        r[i] = -1;
    }
    for (int i = 0; i < nE; i++)
    {
        int a, b;
        in >> a >> b;
        myG[a].push_back(b);
    }
    in.close();
    bool ok = true;
    while (ok)
    {
        ok = false;
        for (int i = 0; i <= nV; i++)
        {
            seen[i] = false;
        }
        for (int i = 1; i <= nV; i++)
        {
            if (l[i] < 0)
            {
                if (visit(myG, l, r, seen, i))
                {
                    ok = true;
                }
            }
        }
    }
    int sum = 0;
    for (int i = 1; i <= nV; i++)
    {
        if (l[i] > 0)
        {
            sum++;
        }
    }
    out << sum << '\n';
    for (int i = 1; i <= nV; i++)
    {
        if (l[i] > 0)
        {
            out << i << ' ' << l[i] << '\n';
        }
    }
    out.close();
    return 0;
}