#include <bits/stdc++.h>

using namespace std;

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


const int NMAX = 1e5 + 5;

int N, M, X, Y, K, St[NMAX], Dr[NMAX], ans;
bool Use[NMAX];

vector < int > G[NMAX];

int cupleaza(int nod)
{

    Use[nod] = true;
    for(auto i : G[nod])
        if(!Dr[i])
        {
            St[nod] = i;
            Dr[i] = nod;
            return 1;
        }
    for(auto i : G[nod])
        if(!Use[Dr[i]] && cupleaza(Dr[i]))
        {
            St[nod] = i;
            Dr[i] = nod;
            return 1;
        }
    return 0;
}

int Cuplaj_Maxim()
{

    ans = 0;

    bool ok = true;
    while (ok)
    {

        ok = false;
        memset(Use, false, sizeof(Use));
        for(int i = 1 ; i<=N; i++)
            if(!Use[i] && !St[i])
                ok |= cupleaza(i);
    }

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

    return ans;

}


int main()
{
    f >> N >> M >> K;

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

        G[X].push_back(Y);
    }

    ans = Cuplaj_Maxim();

    g << ans << '\n';

    for(int i = 1; i <= N; ++i)
        if(St[i])
            g << i << ' ' << St[i] << '\n';

    return 0;
}