#include <bits/stdc++.h>
using namespace std;
void debug_out() { cerr << endl; }
template<class T> ostream& prnt(ostream& out, T v) { out << v.size() << '\n'; for(auto e : v) out << e << ' '; return out;}
template<class T> ostream& operator<<(ostream& out, vector <T> v) { return prnt(out, v); }
template<class T> ostream& operator<<(ostream& out, set <T> v) { return prnt(out, v); }
template<class T1, class T2> ostream& operator<<(ostream& out, map <T1, T2> v) { return prnt(out, v); }
template<class T1, class T2> ostream& operator<<(ostream& out, pair<T1, T2> p) { return out << '(' << p.first << ' ' << p.second << ')'; }
template <typename Head, typename... Tail> void debug_out(Head H, Tail... T) { cerr << " " << H; debug_out(T...);}
#define dbg(...) cerr << #__VA_ARGS__ << " ->", debug_out(__VA_ARGS__)
#define dbg_v(x, n) do{cerr<<#x"[]: ";for(int _=0;_<n;++_)cerr<<x[_]<<" ";cerr<<'\n';}while(0)
#define dbg_ok cerr<<"OK!\n"
#define ll long long
#define ld long double
#define ull unsigned long long
#define pii pair<int,int>
#define MOD 1000000007
#define zeros(x) x&(x-1)^x
#define fi first
#define se second
#define NMAX 10005
const long double PI = acos(-1);

int n, m, e, uz[2 * NMAX], st[2 * NMAX], dr[2 * NMAX];
vector<int> v[2 * NMAX];

bool cup(int nod) {
  uz[nod] = 1;
  for (auto it : v[nod]) {
    if (!st[it]) {
      st[it] = nod;
      dr[nod] = it;
      return 1;
    }
  }

  for (auto it : v[nod]) {
    if (!uz[st[it]] && cup(st[it])) {
      st[it] = nod;
      dr[nod] = it;
      return 1;
    }
  }
  return 0;
}

int main(){
  ios::sync_with_stdio(false);
  freopen("cuplaj.in", "r", stdin);
  freopen("cuplaj.out", "w", stdout);
  cin >> n >> m >> e;
  for (int i=1;i<=e;i++) {
    int a, b;
    cin >> a >> b;
    b += NMAX;
    v[a].push_back(b);
    v[b].push_back(a);
  }

  int ok = 1;
  while (ok) {
    ok = 0;
    memset(uz, 0, sizeof(uz));
    for (int i=1;i<=n;i++) {
      if (!uz[i] && !dr[i]) {
        ok |= cup(i);
      }
    }
  }

  int ans = 0;
  for (int i=1;i<=n;i++) {
    if (dr[i]) ans++;
  }

  cout << ans << '\n';
  for (int i=1;i<=n;i++) {
    if (dr[i]) cout << i << ' ' << dr[i] - NMAX << '\n';
  }


  return 0;
}