#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define MAXN 100005
#include <vector>
#include <list>

struct nod {
  int max_flow;
  int current_flow;
  int id;
};

std::vector<struct nod> v[2 * MAXN];

int prev[2 * MAXN];

int l, r, e;
int viz[2 * MAXN];

int bfs(int src, int dst) {
  std::list<int> q;
  q.push_back(src);
  int cur;
  for (int i = 0; i < l + r + 2; i++) {
    viz[i] = 0;
    prev[i] = -1;
  }
  viz[src] = 1;
  int found = 0;
  while (q.size() && !found) {
    cur = q.front();
    q.pop_front();
    for (unsigned int i = 0; i < v[cur].size(); i++) {
      if (v[cur][i].current_flow < v[cur][i].max_flow && !viz[v[cur][i].id]) {
        if (v[cur][i].id == dst) found = 1;
        q.push_back(v[cur][i].id);
        prev[v[cur][i].id] = cur;
        viz[v[cur][i].id] = 1;
      }
    }
  }
  if (!found) return 0;
  int poz = dst;
  //printf("Found route\n");
  //printf("%d\n", poz);
  while (prev[poz] != -1) {
    for (unsigned int i = 0; i < v[prev[poz]].size(); i++) {
      if (v[prev[poz]][i].id == poz) {
        v[prev[poz]][i].current_flow += 1; break;
      }
    }
    for (unsigned int i = 0; i < v[poz].size(); i++) {
      if (v[poz][i].id == prev[poz]) {
        v[poz][i].current_flow -= 1; break;
      }
    }
    poz = prev[poz];
    //printf("%d\n", poz);
  }
  return 1;
}
int main() {
  //printf("Start?\n");
  FILE *f = fopen("cuplaj.in", "r");
  FILE *g = fopen("cuplaj.out", "w");

  fscanf(f, "%d %d %d", &l, &r, &e);
  for (int i = 0; i < e; i++) {
    int x, y;
    fscanf(f, "%d %d", &x, &y);
    nod new_nod;
    new_nod.max_flow = 1;
    new_nod.current_flow = 0;
    new_nod.id = y + l;
    v[x].push_back(new_nod);
    new_nod.id = x;
    v[y + l].push_back(new_nod);
  }

  for (int i = 0; i < l; i++) {
    nod new_nod;
    new_nod.max_flow = 1;
    new_nod.current_flow = 0;
    new_nod.id = i + 1;
    v[0].push_back(new_nod);
  }
  for (int i = 0; i < r; i++) {
    nod new_nod;
    new_nod.max_flow = 1;
    new_nod.current_flow = 0;
    new_nod.id = l + r + 1;
    v[l + i + 1].push_back(new_nod);
  }
  int cnt = 0;
  //printf("Starting BFS\n");
  /*while (bfs(0, l + r + 1)) {
    cnt++;
    //printf("%d\n", cnt);
  }*/

  fprintf(g, "%d\n", cnt);
  for (int i = 1; i <= l; i++) {
    for (unsigned int j = 0; j < v[i].size(); j++) {
      if (v[i][j].current_flow == 1) {
        fprintf(g, "%d %d\n", i, v[i][j].id - l); break;
      }
    }
  }
  return 0;
}