#include<bits/stdc++.h>
using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
typedef long long ll;
typedef long double ld;

const int N = 1e4 + 5;
int n, m, e, cpl[2 * N], rasp;
bool viz[N];
vector<int> v[N];

bool pairUp(int nod)
{
    if (viz[nod])
        return false;
    viz[nod] = true;
    for (int i : v[nod])
        if (!cpl[i])
        {
            cpl[i] = nod;
            cpl[nod] = i;
            return true;
        }
    for (int i : v[nod])
        if (pairUp(cpl[i]))
        {
            cpl[i] = nod;
            cpl[nod] = i;
            return true;
        }
    return false;
}

int main()
{
    fin >> n >> m >> e;
    while (e--)
    {
        int a, b;
        fin >> a >> b;
        v[a].push_back(b + n);
    }
    bool gasit;
    do
    {
        gasit = false;
        for (int i = 1; i <= n; i++)
            viz[i] = false;
        for (int i = 1; i <= n; i++)
            if (!cpl[i] && pairUp(i))
            {
                rasp++;
                gasit = true;
            }
    } while (gasit);
    fout << rasp << '\n';
    for (int i = 1; i <= n; i++)
        if (cpl[i])
            fout << i << ' ' << cpl[i] - n << '\n';
    return 0;
}