#include <iostream>
#include <fstream>
#include <vector>
#include <bitset>
using namespace std;
ifstream in("cuplaj.in");
ofstream out("cuplaj.out");
const int maxn = 10005;
vector <pair <int, int> > sol;
vector <int> v[maxn];
bitset <maxn> viz;
int dreapta[maxn];
int stanga[maxn];
int n;

bool cupleaza(int nod)
{
    if(viz[nod] == 1)
        return 0;
    viz[nod] = 1;
    for(auto it : v[nod])
    {
        if(stanga[it] == 0)
        {
            stanga[it] = nod;
            dreapta[nod] = it;
            return 1;
        }
    }
    for(auto it : v[nod])
    {
        if(!viz[stanga[it]] && cupleaza(stanga[it]))
        {
            stanga[it] = nod;
            dreapta[nod] = it;
            return 1;
        }
    }
    return 0;
}

void cuplaj()
{
    bool ok = 1;
    while(ok == 1)
    {
        ok = 0;
        viz.reset();
        for(int i = 1; i <= n; i++)
            if(dreapta[i] == 0 && cupleaza(i))
                ok = 1;
    }
}

int main()
{
    int m, E;
    in >> n >> m >> E;
    for(int i = 1; i <= E; i++)
    {
        int x, y;
        in >> x >> y;
        v[x].push_back(y);
    }
    cuplaj();
    for(int i = 1; i <= n; i++)
        if(dreapta[i] > 0)
            sol.push_back(make_pair(i, dreapta[i]));
    out << sol.size() << "\n";
    for(auto it : sol)
        out << it.first << " " << it.second << "\n";
    return 0;
}