#include<fstream>
#include<vector>
#include<cstring>
#define NMAX 10005
using namespace std;
vector<int> G[NMAX];
int n, m, nm, i, x, y;
int fiu, card;
int R[NMAX], L[NMAX];
bool u[NMAX];
bool check_cuplaj;
ifstream cin("cuplaj.in");
ofstream cout("cuplaj.out");
bool cupleaza(int nod)
{
    if(u[nod] == 1)
    {
        return 0;
    }
    u[nod] = 1;
    for(int i = 0; i < G[nod].size(); i++)
    {
        int fiu = G[nod][i];
        if(L[fiu] == 0)
        {
            R[nod] = fiu;
            L[fiu] = nod;
            return 1;
        }
    }
    for(int i = 0; i < G[nod].size(); i++)
    {
        int fiu = G[nod][i];
        if(cupleaza(L[fiu]))
        {
            R[nod] = fiu;
            L[fiu] = nod;
            return 1;
        }
    }
    return 0;
}
void reinit()
{
    memset(u, 0, sizeof(u));
}
void incearca_cuplaje()
{
    do
    {
        reinit();
        check_cuplaj = 0;
        for(i = 1; i <= n; i++)
        {
            if(R[i] == 0)
            {
                check_cuplaj |= cupleaza(i);
            }
        }
    }
    while(check_cuplaj);
}
void find_card()
{
    for(i = 1; i <= n; i++)
    {
        if(R[i] != 0)
        {
            card++;
        }
    }
}
void afisare()
{
    cout << card << "\n";
    for(i = 1; i <= n; i++)
    {
        if(R[i] != 0)
        {
            cout << i << " " << R[i] << "\n";
        }
    }
}
int main()
{
    cin >> n >> m >> nm;
    for(i = 1; i <= nm; i++)
    {
        cin >> x >> y;
        G[x].push_back(y);
    }
    incearca_cuplaje();
    find_card();
    afisare();
}