#include <algorithm>
#include <iostream>
#include <fstream>
#include <bitset>
#include <vector>
#include <queue>

using namespace std;

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

const int NMAX = 1e4;

int n, m, e;
int dist[1 + 2 * NMAX];
int match[1 + 2 * NMAX];

bitset < 1 + 2 * NMAX > vis;
vector < int > g[1 + 2 * NMAX];

void addedge(int x, int y) {
  g[x].push_back(y);
  g[y].push_back(x);
}

void bfs() {
  fill(dist + 1, dist + n + m + 1, -1);
  queue < int > q;
  for(int i = 1; i <= n; i++) {
    if(match[i] <= 0) {
      q.push(i);
      dist[i] = 0;
    }
  }

  while(!q.empty()) {
    int u1 = q.front();
    q.pop();
    for(int i = 0; i < g[u1].size(); i++) {
      int v1 = g[u1][i];
      int u2 = match[v1];
      if(0 < u2 && dist[u2] < 0) {
        dist[u2] = dist[u1] + 1;
        q.push(u2);
      }
    }
  }
}

bool dfs(int u1) {
  vis[u1] = 1;
  for(int i = 0; i < g[u1].size(); i++) {
    int v1 = g[u1][i];
    int u2 = match[v1];
    if(match[v1] <= 0) {
      match[u1] = v1;
      match[v1] = u1;
      return true;
    } else if(vis[u2] == 0 && dist[u2] == dist[u1] + 1) {
      if(dfs(u2) == 1) {
        match[u1] = v1;
        match[v1] = u1;
        return true;
      }
    }
  }
  return false;
}

int maxmatching() {
  int answer = 0, add = 1;
  while(0 < add) {
    bfs();
    vis = 0;

    add = 0;
    for(int i = 1; i <= n; i++) {
      if(match[i] <= 0){
        if(dfs(i) == true)
          add++;
      }
    }
    answer += add;
  }
  return answer;
}

int main()
{
  in >> n >> m >> e;
  for(int i = 1; i <= e; i++) {
    int x, y;
    in >> x >> y;
    addedge(x, y + n);
  }

  out << maxmatching() << '\n';
  for(int i = 1; i <= n; i++) {
    if(0 < match[i])
      out << i << ' ' << match[i] - n << '\n';
  }

  in.close();
  out.close();
  return 0;
}