#include <bits/stdc++.h>

using namespace std;

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

const int NMAX = 1e4 + 5;

int N, M, E, X, Y, L[NMAX], R[NMAX];

bool Marked[NMAX];

vector < int > G[NMAX];

static inline void Read ()
{
    f.tie(NULL);

    f >> N >> M >> E;

    for(int i = 1; i <= E; ++i)
    {
        f >> X >> Y;

        G[X].push_back(Y);
    }

    return;
}

static inline bool Cupleaza (int Node)
{
    Marked[Node] = 1;

    for(auto it : G[Node])
        if(!R[it])
        {
            L[Node] = it;
            R[it] = Node;

            return true;
        }

    for(auto it : G[Node])
        if(!Marked[R[it]] && Cupleaza(R[it]))
        {
            L[Node] = it;
            R[it] = Node;

            return true;
        }

    return false;
}

static inline int Match ()
{
    bool done = 1;

    while(done)
    {
        done = 0;

        for(int i = 1; i <= N; ++i)
            Marked[i] = false;

        for(int i = 1; i <= N; ++i)
            if(!Marked[i])
                if(!L[i])
                    done |= Cupleaza(i);
    }

    int ans = 0;

    for(int i = 1; i <= N; ++i)
        if(L[i])
            ++ans;

    return ans;
}

static inline void Write ()
{
    for(int i = 1; i <= N; ++i)
        if(L[i])
            g << i << ' ' << L[i] << '\n';

    return;
}

int main()
{
    Read();

    g << Match() << '\n';

    Write();

    return 0;
}