#include <iostream>
#include <fstream>
#include <cstring>
#include <vector>

using namespace std;

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

const int dim = 10005;

int n,m,e,saturat[2*dim],corespondenta[2*dim];
vector<int> vec[2*dim];

int Cuplaj(int nod)
{
    if (saturat[nod]) return 0;
    saturat[nod] = 1;
    for (auto y:vec[nod])
    {
        if (corespondenta[y] == -1 || Cuplaj(y))
        {
            corespondenta[y] = nod;
            return 1;
        }
    }
    return 0;
}

int main()
{
    int x,y;
    in >> n >> m >> e;
    for (int i=1; i<=e; i++)
    {
        in >> x >> y;
        vec[x].push_back(n + y);
        vec[n + y].push_back(x);
    }
    for (int i=1; i<=m; i++) corespondenta[n + i] = -1;
    int cate = 0;
    for (int i=1; i<=n; i++)
    {
        memset(saturat, 0, sizeof(saturat));
        Cuplaj(i);
    }
    for (int i=1; i<=m; i++)
    {
        if (corespondenta[n + i] != -1) cate++;
    }
    out << cate << "\n";
    for (int i=1; i<=m; i++)
    {
        if (corespondenta[n + i] != -1) out << corespondenta[n + i] << " " << i << "\n";
    }
    return 0;
}