#include <cstdio>

const int MAX_N = 10000;
const int MAX_M = 100000;

int last[2][1+MAX_N], next[1+2*MAX_M], mc[1+2*MAX_M];
int cuplat[2][1+MAX_N];
bool viz[2][1+MAX_N];

inline void addM(int gr, int a, int b, int id) {
  next[id] = last[gr][a];
  last[gr][a] = id;
  mc[id] = b;
}

bool augment(int node, int gr) {
  int i = last[gr][node];
  viz[gr][node] = true;
  if(gr == 1 && cuplat[gr][node] == 0) {
    return true;
  }
  else if(gr == 1) {
    return augment(cuplat[gr][node], 1-gr);
  } else {
    while(i != 0) {
      if(!viz[1-gr][mc[i]] && augment(mc[i], 1 - gr)) {
        cuplat[gr][node] = mc[i];
        cuplat[1-gr][mc[i]] = node;
        return true;
      }
      i = next[i];
    }
    return false;
  }
}

int main() {
  int n, m, e, a, b, cuplaj;
  FILE *fin = fopen("cuplaj.in", "r");
  fscanf(fin, "%d%d%d", &n, &m, &e);
  for(int i = 0; i < e; ++i) {
    fscanf(fin, "%d%d", &a, &b);
    addM(0, a, b, i * 2 + 1);
    addM(1, b, a, i * 2 + 2);
  }
  fclose(fin);

  bool ok;
  do {
    ok = false;
    for(int i = 1; i <= n; ++i)
      viz[0][i] = false;
    for(int i = 1; i <= m; ++i)
      viz[1][i] = false;
    for(int i = 1; i <= n; ++i)
      if(cuplat[0][i] == 0 && augment(i, 0))
        ok = true;
  } while(ok);

  FILE *fout = fopen("cuplaj.out", "w");
  for(int i = 1; i <= n; ++i)
    if(cuplat[0][i] > 0)
      cuplaj++;
  fprintf(fout, "%d\n", cuplaj);
  for(int i = 1; i <= n; ++i)
    if(cuplat[0][i] > 0)
      fprintf(fout, "%d %d\n", i, cuplat[0][i]);
  fclose(fout);
  return 0;
}
//autismul se manifesta prin cai misterioase
//penalitatea si-a spus cuvantul