#include <fstream>
#include <iostream>
#include <climits>
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");

struct edge{
    int y;
    int capacity;
    int flow;
};

int n, m, x, y, e;

queue<int> q;
int father[20005];
vector<edge> ad[20005];
int source, destination;

bool explored[20005];

bool cmp(edge e1, edge e2) {
    return e1.y < e2.y;
}


int bfs() {

    fill(father + 1, father + n + m + 3, 0);
    fill(explored + 1, explored + n + m + 3, 0);

    explored[source] = 1;
    q.push(source);

    while(!q.empty()) {
        int node = q.front();

        q.pop();

        if(node == destination)
            continue;

        for(auto vec : ad[node]) {
            if(vec.flow < vec.capacity && explored[vec.y] == 0) {
                explored[vec.y] = 1;
                q.push(vec.y);
                father[vec.y] = node;
            }
        }
    }

    if(explored[destination] == 0)
        return 0; // destination can't be reached!
    else
        return 1; // destination reached!
}

int findPosition(int node, int vec){
    if(ad[node].size() <= 50) {
        for(int i = 0; i < ad[node].size(); i ++)
            if(ad[node][i].y == vec)
                return i;
    } else {
        int st = 0;
        int dr = ad[node].size() - 1;
        int mij;
        while(st <= dr) {
            mij = (st + dr) / 2;
            if(ad[node][mij].y == vec)
                return mij;
            else if(ad[node][mij].y < vec)
                st = mij + 1;
            else if(ad[node][mij].y > vec)
                dr = mij - 1;
        }
    }


    return -1;
};

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

    // pun muchiile citite in problema cu capacitate 1
    for (int i = 1; i <= e; i++ )
    {
        fin >> x >> y;
        ad[x].push_back({y + n, 1, 0});
        ad[y + n].push_back({x, 0, 0});
    }

    source = n + m + 2; // aleg un nod sursa
    destination = n + m + 1; // aleg un nod destinatie

    // adaug muchii de capacitate 1 de la sursa la primul set de noduri
    for(int i = 1 ; i <= n ; i++) {
        ad[source].push_back({i, 1, 0});
        ad[i].push_back({source, 0, 0});
    }

    // adaug muchii de capacitate 1 de la al doilea set de noduri la destinatie
    for(int i = n + 1; i <= n + m; i ++) {
        ad[i].push_back({destination, 1, 0});
        ad[destination].push_back({i, 0, 0});
    }

    // sortez listele de adiacenta crescator
    for(int i = 1 ; i <= n + m + 2; i ++)
        sort(ad[i].begin(), ad[i].end(), cmp);



    int max_flow = 0;
//return 0;
    while(bfs()) {
        //cout << "ceva" << '\n';
        int min_flow = INT_MAX;
        for(auto vec : ad[destination]) {
            int pos = findPosition(vec.y, destination);
            if (explored[vec.y] == 0 || ad[vec.y][pos].flow == ad[vec.y][pos].capacity)
                continue;

            int node = destination;
            father[destination] = vec.y;

            while (father[node] != 0) {
                int pos1 = findPosition(father[node], node);

                min_flow = min(min_flow, ad[father[node]][pos1].capacity - ad[father[node]][pos1].flow);
                node = father[node];
            }

            node = destination;
            max_flow += min_flow;

            while (father[node] != 0) {
                int pos1 = findPosition(father[node], node);
                ad[father[node]][pos1].flow += min_flow;

                int pos2 = findPosition(node, father[node]);
                ad[node][pos2].flow -= min_flow;
                node = father[node];
            }
        }
    }

    fout << max_flow << '\n';

    for(int i = 1; i <= n ; i ++)
        for(auto j : ad[i]) {
            if(j.flow == 1)
                fout << i << " " << j.y - n << '\n';
        }
    return 0;
}