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

using namespace std;

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

const int dim = 1e4 + 4;

int n,m,k;
int corespondenta[dim],saturat[dim];
vector<int> vec[dim];

int Cuplaj(int nod)
{
    if (saturat[nod]) return 0;

    saturat[nod] = 1;

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

int main(){

    in >> n >> m >> k;

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