#include <bits/stdc++.h>
#define dim 100005
#define range(a, b, var) for(int var=a;var<=b;++var)

using namespace std;

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

struct Nod {
    int fr=0, st=0, dr=0;
};

int n, m, e, x, y, sol;
bool running;
vector<int> a[dim];

Nod fr[dim];

bool cDreapta(int nod);

bool cStanga(int nod);

bool cupleaza(int nod) {
    if (fr[nod].fr == 1) return false;
    fr[nod].fr = 1;
    return cDreapta(nod) || cStanga(nod);
}

int main() {
    fin >> n >> m >> e;

    range(1, e, i) {
        fin >> x >> y;
        a[x].push_back(y);
    }


    running = true;
    while (running) {
        range(1, max(n, m), i)
            fr[i].fr = 0;
        running = false;
        range(1, n, i)
            if (fr[i].st == 0)
                running |= cupleaza(i);
    }

    fout << sol << "\n";
    range(1, n, i)
        if (fr[i].st != 0)
            fout << i << " " << fr[i].st << "\n";
}


bool cDreapta(int nod) {
    for (int vecin: a[nod])
        if (fr[vecin].dr == 0) {
            fr[vecin].dr = nod;
            fr[nod].st = vecin;
            sol++;
            return true;
        }
    return false;
}

bool cStanga(int nod) {
    for (int vecin: a[nod])
        if (cupleaza(fr[vecin].dr) == true) {
            fr[vecin].dr = nod;
            fr[nod].st = vecin;
            return true;
        }
    return false;
}