/*
 * Edmonds-Karp's algorithm
 * Complexity: O(V*E^2)
 * https://www.infoarena.ro/problema/cuplaj
 */
#include <bits/stdc++.h>

using namespace std;

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

int leftSize, rightSize, edges, s, t;
vector<int> parrent;
vector<vector<int>> adjListRes;
vector<vector<int>> capacity;

void addEdge(int u, int v){
    adjListRes[u].push_back(v);
    adjListRes[v].push_back(u);
    capacity[u][v] = 1;
}

void init() {
    s = 0;
    t = leftSize+rightSize+1;
    parrent.resize(t+1);
    adjListRes.resize(t+1);
    capacity.resize(t+1, vector<int>(t+1));
    for(int i = 1; i <= leftSize; i++)
        addEdge(s, i);
    for(int i = 1; i <= rightSize; i++)
        addEdge(leftSize+i, t);
}

void read(){
    in >> leftSize >> rightSize >> edges;
    init();
    for(int i = 1; i <= edges; i++){
        int u, v;
        in >> u >> v;
        addEdge(u, leftSize + v);
    }
}

bool bf(){
    vector<bool> visited(t);
    queue<int> q;
    q.push(s);
    visited[s] = true;
    parrent[s] = -1;
    while(!q.empty()){
        int u = q.front();
        q.pop();
        for(auto v: adjListRes[u]){
            if(!visited[v] and capacity[u][v]){
                parrent[v] = u;
                if(v == t)
                    return true;
                visited[v] = true;
                q.push(v);
            }
        }
    }
    return false;
}

int maxFlow(){
    long max_flow = 0;
    set<int> temp;
    while(bf()){
        int u, v, path_flow = INT_MAX;
        for(v = t; v != s; v = parrent[v]){
            u = parrent[v];
            if(capacity[u][v] < path_flow)
                path_flow = capacity[u][v];
        }
        for(v = t; v != s; v = parrent[v]){
            u = parrent[v];
            capacity[u][v] -= path_flow;
            capacity[v][u] += path_flow;
        }
        max_flow += path_flow;
    }
    return max_flow;
}

int main() {
    read();
    out << maxFlow() << '\n';
    vector<pair<int, int>> solution;
    for(int u = 1; u <= leftSize; u++)
        for(auto v: adjListRes[u])
            if(!capacity[u][v] && v)
                out << u << " " << v-leftSize << '\n';
    return 0;
}