#include <iostream>
#include <cstdio>
#include <vector>
#include <bitset>

#define nmax 10005

using namespace std;

int n, m, e;
vector <int> G[nmax];
bitset <nmax> viz;
int L[nmax], R[nmax];
int nrm = 0;

void citire()
{
    scanf("%d %d %d",&n, &m, &e);
    for (int i=1; i<=e; i++)
    {
        int x, y;
        scanf("%d %d",&x, &y);
        G[x].push_back(y);
    }
}

int cuplaj(int x)
{
    if (viz[x])
        return 0;
    viz[x] = 1;
    for (int i=0; i<G[x].size(); i++)
        if (!R[G[x][i]] || cuplaj(R[G[x][i]]))
        {
            L[x] = G[x][i];
            R[G[x][i]] = x;
            return 1;
        }
    return 0;
}

void rezolvare()
{
    int ok = 1;
    while (ok)
    {
        ok = 0;
        viz = 0;
        for(int i=1; i <= n; i++)
            if(!L[i] && cuplaj(i))
            {
                nrm++;
                ok = 1;
            }
    }
}

void afisare()
{
    printf("%d\n",nrm);
    for (int i=1; i<=n; i++)
        if (L[i])
            printf("%d %d\n",i, L[i]);

}

int main()
{
    freopen("cuplaj.in","r",stdin);
    freopen("cuplaj.out","w",stdout);
    citire();
    rezolvare();
    afisare();

    return 0;
}