#include <fstream>
#include <vector>
#include <cstring>

using namespace std;

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

int n, m, e, i, j, x, y, nr;
int st[10005], dr[10005];
bool ok, viz[10005];
vector <int> ls[10005];

bool uneste(int x) {
    if (viz[x])
        return 0;
    int i, l = ls[x].size(), y;
    viz[x] = 1;
    for (i = 0; i < l; i++) {
        y = ls[x][i];
        if (dr[y] == 0) {
            st[x]=y;
            dr[y]=x;
            return 1;
        }
    }
    for (i = 0; i < l; i++) {
        y = ls[x][i];
        if (uneste(dr[y])) {
            st[x]=y;
            dr[y]=x;
            return 1;
        }
    }
    return 0;
}

int main() {
    f >> n >> m >> e;
    while (e--) {
        f >> x >> y;
        ls[x].push_back(y);
    }

    ok = 1;
    while (ok) {
        ok = nr = 0;
        memset(viz, 0, sizeof(viz));
        for (i = 1; i <= n; i++)
            if (st[i] == 0 && uneste(i))
                ok = 1, nr++;
    }
    for (i = 1; i <= n; i++)
        nr+=(st[i]>0);
    g << nr << '\n';
    for (i = 1; i <= n; i++)
        if (st[i])
            g << i << ' ' << st[i] << '\n';
    return 0;
}