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

using namespace std;

const int AMax = 10010, BMax = 10010, MMax = 100010;
bool viz[AMax];
int nra, nrb, ncuplaje;
int st[AMax], dr[BMax];
vector <int> G[AMax];

void Read()
{
    ifstream f("cuplaj.in");
    int m;
    f>>nra>>nrb>>m;
    for (int i = 1; i<=m; ++i)
    {
        int x, y; f>>x>>y;
        G[x].push_back(y);
    }
    f.close();
}

inline bool Hopcroft_Karp(const int &node)
{
    if (viz[node])
        return false;
    viz[node] = true;
    for (vector <int> :: iterator it = G[node].begin(); it != G[node].end(); ++it)
        if (!st[*it])
        {
            st[*it] = node;
            dr[node] = *it;
            return true;
        }
    for (vector <int> :: iterator it = G[node].begin(); it != G[node].end(); ++it)
        if (Hopcroft_Karp(st[*it]))
        {
            dr[node] = *it;
            st[*it] = node;
            return true;
        }
    return false;
}

void Solve()
{
    for (bool change = true; change; )
    {
        change = false;
        for (int i = 1; i<=nra; ++i)
            if (!dr[i])
                if (Hopcroft_Karp(i))
                    change = true;
        for (int i = 1; i<=nra; ++i)
            viz[i] = false;
    }
}

void Write()
{
    for (int i = 1; i<=nra; ++i)
        if (dr[i])
            ++ncuplaje;
    ofstream g("cuplaj.out");
    g<<ncuplaje<<"\n";
    for (int i = 1; i<=nra; ++i)
        if (dr[i])
            g<<i<<" "<<dr[i]<<"\n";
    g.close();
}

int main()
{
    Read();
    Solve();
    Write();
    return 0;
}