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

using namespace std;

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

const int NMAX = 20000 + 5;

struct Edge{
  int to;
  int rev;
  int cap;
  int flow;
};

int n, m, e;
int tot, src, dest;
int rem[1 + NMAX];
int dist[1 + NMAX];

vector < Edge > g[1 + NMAX];

void addedge(int i, int j){
  Edge direct = {j, g[j].size(), 1, 0};
  Edge inverse = {i, g[i].size(), 0, 0};
  g[i].push_back(direct);
  g[j].push_back(inverse);
}

void read(){
  in >> n >> m >> e;
  tot = n + m;
  src = 0;
  dest = tot + 1;

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

bool bfs(){
  queue < int > q;
  fill(dist, dist + tot + 2, -1);
  dist[src] = 0;
  q.push(src);
  while(!q.empty()){
    int from = q.front();
    q.pop();
    for(int i = 0; i < g[from].size(); i++){
      Edge &e = g[from][i];
      if(dist[e.to] < 0 && e.flow < e.cap){
        dist[e.to] = dist[from] + 1;
        q.push(e.to);
      }
    }
  }
  return (0 <= dist[dest]);
}

int dfs(int from, int deltaflow){
  if(from == dest)
    return deltaflow;
  else{
    for(int i = 0; i < g[from].size(); i++){
      Edge &e = g[from][i];
      if(dist[from] + 1 == dist[e.to]){
        int addflow = dfs(e.to, min(deltaflow, e.cap - e.flow));
        if(0 < addflow){
          e.flow += addflow;
          g[e.to][e.rev].flow -= addflow;
          rem[from] = i;
          return addflow;
        }
      }
    }
    return 0;
  }
}

int maxflow(){
  int result = 0;
  while(bfs()){
    fill(rem, rem + tot + 2, 0);
    while(int deltaflow = dfs(src, INT_MAX)){
      result += deltaflow;
    }
  }
  return result;
}

void tracesol(){
 for(int i = 1; i <= n; i++){
  for(int j = 0; j < g[i].size(); j++){
    Edge &e = g[i][j];
    //cout << i << " " << g[i][j].to << ' ' << g[i][j].flow << ' ' << g[i][j].cap << '\n';
    if(e.flow == 1){
      out << i << ' ' << e.to - n << '\n';
      break;
    }
  }
 }
}

int main(){
  read();
  out << maxflow() << '\n';
  tracesol();

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