#include <fstream>
#include <vector>
#include <iostream>
using namespace std;

int n, m, e;
int sol;
vector<int> a[10001];

void read() {
    int i, x, y;
    ifstream f("cuplaj.in");
    f >> n >> m >> e;
    for (i = 1; i <= e; i++) {
        f >> x >> y;
        a[x].emplace_back(y);
    }
    f.close();
}   

int viz[10001];
int r[10001];
int l[10001];

bool pair_up(int x) {
    int i, p;
    viz[x] = 1;
    for (i = 0; i < a[x].size(); i++) {
        p = a[x][i];
        if (l[p] == 0) {
            r[x] = p;
            l[p] = x;
            return 1;
        }
    }
    for (i = 0; i < a[x].size(); i++) {
        p = a[x][i];
        if (!viz[l[p]] && pair_up(l[p])) {
            r[x] = p;
            l[p] = x;
            return 1;
        }
    }
    return 0;
}

void solve() {
    bool ok;
    int i;
    do {
        ok = 0;
        for (i = 1; i <= n; i++)
            viz[i] = 0;
        for (i = 1; i <= n; i++)
            if (r[i] == 0 && pair_up(i))
                ok = 1;
    } while(ok == 1);
    for (i = 1; i <= n; i++)
        if (r[i])
            sol++;
}

void output() {
    int i;
    ofstream g("cuplaj.out");
    g << sol << '\n';
    for (i = 1; i <= n; i++)
        if (r[i])
            g << i << ' ' << r[i] << '\n';
    g.close();
}

int main() {
    read();
    solve();
    output();
    return 0;
}