#include <fstream>
#include <vector>
#include <bitset>

using namespace std;

const int nmx = 10002;

int ns,nd,m;
int d[nmx], s[nmx];
vector <int> g[nmx];
bitset <nmx> viz;

void citire()
{
    scanf("%d %d %d", &ns, &nd, &m);
    for(int i = 1; i <= m; ++i)
    {
        int nod1,nod2;
        scanf("%d %d", &nod1, &nod2);
        g[nod1].push_back(nod2);
    }
}

bool incercare(int nod)
{
    if(viz[nod])
        return false;
    viz[nod] = true;

    for(vector<int>::iterator it = g[nod].begin(); it != g[nod].end(); ++it)
        if(not d[*it])
        {
            d[*it] = nod;
            s[nod] = *it;
            return true;
        }

    for(vector<int>::iterator it = g[nod].begin(); it != g[nod].end(); ++it)
        if(incercare(d[*it]))
        {
            d[*it] = nod;
            s[nod] = *it;
            return true;
        }

    return false;
}

void rezolvare()
{
    bool schimbare = true;

    while(schimbare)
    {
        schimbare = false;
        viz.reset();
        for(int i = 1; i <= ns; ++i)
            if(not s[i])
                schimbare |= incercare(i);
    }
}

void afish()
{
    int total = 0;

    for(int i = 1; i <= ns; ++i)
        if(s[i])
            ++ total;

    printf("%d\n", total);
    for(int i = 1; i <= ns; ++i)
        if(s[i])
            printf("%d %d\n", i, s[i]);
}

int main()
{
    freopen("cuplaj.in", "r", stdin);
    freopen("cuplaj.out", "w", stdout);
    citire();
    rezolvare();
    afish();
    return 0;
}