#include <iostream>
#include <cstdio>
#include <vector>

using namespace std;

const int NMAX = 10000;

int n, m, e;
vector<int> vst[NMAX + 5];

int st[NMAX + 5];
int dr[NMAX + 5];
bool viz[NMAX + 5];

bool alternating_path(int nod_st) {
  if(viz[nod_st])
    return false;
  viz[nod_st] = true;

  for(int nod_dr : vst[nod_st]) {
    if(nod_dr == dr[nod_st])
      continue;

    if(st[nod_dr] == 0 || alternating_path(st[nod_dr])) {
      st[nod_dr] = nod_st;
      dr[nod_st] = nod_dr;
      return true;
    }
  }

  return false;
}

int main() {
  freopen("cuplaj.in", "r", stdin);
  freopen("cuplaj.out", "w", stdout);

  scanf("%d %d %d", &n, &m, &e);
  for(int i = 1; i <= e; i++) {
    int x, y;
    scanf("%d %d", &x, &y);
    vst[x].push_back(y);
  }

  int cuplaj_max = 0;
  int old_cuplaj;
  do {
    old_cuplaj = cuplaj_max;
    for(int i = 1; i <= n; i++)
      viz[i] = false;

    for(int i = 1; i <= n; i++)
      if(dr[i] == 0)
        cuplaj_max += alternating_path(i);
  } while(cuplaj_max != old_cuplaj);

  printf("%d\n", cuplaj_max);
  for(int i = 1; i <= n; i++)
    if(dr[i] != 0)
      printf("%d %d\n", i, dr[i]);

  return 0;
}