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

#define MAXN  10005

using namespace std;

int N, M, E;
vector <int> G[MAXN];
int st[MAXN], dr[MAXN];
bitset <MAXN> marcat;

int cupleaza(int nod) {
    if (marcat[nod]) {
        return 0;
    }
    marcat[nod] = 1;

    for (int vecin : G[nod]) {
        if (!dr[vecin]) { // daca vecinul din dreapta n-are pereche
            st[nod] = vecin;
            dr[vecin] = nod;
            return 1;
        }
    }

    // daca n-am cu cine sa imperechem nodul (toti vecinii din partea
    // dreapta sunt deja imperecheati)
    for (int vecin : G[nod]) {
        if (cupleaza(dr[vecin])) {
            st[nod] = vecin;
            dr[vecin] = nod;
            return 1;
        }
    }

    return 0;
}

int main()
{
    iostream::sync_with_stdio(false);
    freopen("cuplaj.in", "r", stdin);
    freopen("cuplaj.out", "w", stdout);

    cin >> N >> M >> E;
    for (int i = 1; i <= E; ++i) {
        int x, y;
        cin >> x >> y;
        G[x].push_back(y);
    }

    int cuplaj = 0;
    for (int i = 1; i <= N; ++i) {
        if (!cupleaza(i)) {
            marcat.reset();
            cuplaj += cupleaza(i);
        } else {
            cuplaj++;
        }
    }

    cout << cuplaj << "\n";
    for (int i = 1; i <= N; ++i) {
        if (st[i] != 0) {
            cout << i << " " << st[i] << "\n";
        }
    }

    return 0;
}