#include <fstream>
#include <vector>
#include <algorithm>

using namespace std;

const int NIL = -1;

vector< vector<int> > G;
int V, L, R;
vector<int> Pair;
vector<bool> Used;
vector< pair<int, int> > Matching;

int PairUp(const int x) {
    if (x == NIL || Used[x])
        return 0;
    Used[x] = true;
    for (vector<int>::const_iterator y = G[x].begin(); y != G[x].end(); ++y) {
        if (Pair[*y] == NIL || PairUp(Pair[*y])) {
            Pair[x] = *y;
            Pair[*y] = x;
            return 1;
        }
    }
    return 0;
}

vector< pair<int, int> > GetMaximumMatching() {
    Pair = vector<int>(V, NIL);
    for (int change = 1; change > 0; ) {
        change = 0;
        Used = vector<bool>(L, false);
        for (int x = 0; x < L; ++x)
            if (Pair[x] == NIL)
                change |= PairUp(x);
    }
    vector< pair<int, int> > matching;
    for (int x = 0; x < L; ++x)
        if (Pair[x] != NIL)
            matching.push_back(make_pair(x, Pair[x]));
    return matching;
}

void Solve() {
    Matching = GetMaximumMatching();
}

inline void AddEdge(const int x, const int y) {
    G[x].push_back(y);
    G[y].push_back(x);
}

void Read() {
    ifstream cin("cuplaj.in");
    int E;
    cin >> L >> R >> E;
    V = L + R;
    G = vector< vector<int> >(V, vector<int>());
    for (; E > 0; --E) {
        int x, y;
        cin >> x >> y;
        AddEdge(x - 1, y - 1 + L);
    }
    cin.close();
}

void Print() {
    ofstream cout("cuplaj.out");
    cout << int(Matching.size()) << "\n";
    for (vector< pair<int, int> >::const_iterator e = Matching.begin(); e != Matching.end(); ++e)
        cout << e->first + 1 << " " << e->second + 1 - L << "\n";
    cout.close();
}

int main() {
    Read();
    Solve();
    Print();
    return 0;
}