#include <iostream>
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

ifstream in("cuplaj.in");
ofstream out ("cuplaj.out");

#define inf (1<<30)
const int N = 10002;
int n, m, e, st[N], dr[N], rez, col[N];
bool viz[N];
vector <int> v[N];
queue < pair<int, int> > q;

bool bipartit(int nod) {
    col[nod] = 1;
    q.push(make_pair(nod, col[nod]));
    while (!q.empty()) {
        int x = q.front().first;
        int cx = q.front().second;
        q.pop();
        for (int i = 0; i < v[x].size(); i++) {
            int y = v[x][i];
            if (col[y] == -1) {
                col[y] = 1 - col[x];
                q.push(make_pair(y, col[y]));
            }
            else if (col[y] == col[x])
                return false;
        }
    }
    return true;
}

bool cuplaj (int x) {
    if (viz[x])
        return false;
    viz[x] = true;
    for (int i = 0; i < v[x].size(); i++) {
        int y = v[x][i];
        if (!dr[y]) {
            dr[y] = x;
            st[x] = y;
            return true;
        }
    }
    for (int i = 0; i < v[x].size(); i++) {
        int y = v[x][i];
        if (cuplaj(dr[y])) {
            st[x] = y;
            dr[y] = x;
            return true;
        }
    }
    return false;
}

int main() {
    in >> n >> m >> e;
    int x, y;
    for (int i = 0; i < e; i++) {
        in >> x >> y;
        v[x].push_back(y);
    }
    if (bipartit(1));

    int flag = 0;
    while (!flag) {
        flag = 1;
        for (int i = 1; i <= n + m; i++)
            viz[i] = false;
        for (int i = 1; i <= n; i++) {
            if (!st[i] && cuplaj(i)) {
                rez++;
                flag = 0;
            }
        }
    }

    out << rez << '\n';
    for (int i = 1; i <= n; i++) {
        if (st[i] > 0) {
            out << i << ' ' << st[i] << '\n';
        }
    }
    return 0;
}