#include <bits/stdc++.h>
#define ll long long
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pli pair<ll,int>
#define pil pair<int,ll>
#define fi first
#define se second
#define inf (INT_MAX/2-1)
#define infl (1LL<<60)
#define vi vector<int>
#define vl vector<ll>
#define pb push_back
#define sz(a) (int)(a).size()
#define all(a) begin(a),end(a)
#define y0 y5656
#define y1 y7878
#define aaa system("pause");
#define dbg(x) cerr<<(#x)<<": "<<(x)<<'\n',aaa
#define dbga(x,n) cerr<<(#x)<<"[]: ";for(int _=0;_<n;_++)cerr<<x[_]<<' ';cerr<<'\n',aaa
#define dbgs(x) cerr<<(#x)<<"[stl]: ";for(int _:x)cerr<<_<<' ';cerr<<'\n',aaa
#define dbgp(x) cerr<<(#x)<<": "<<x.fi<<' '<<x.se<<'\n',aaa
#define maxn 10000

using namespace std;

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

vi g[2*maxn+5];
int bip[2*maxn+5];
bool viz[2*maxn+5];
int n, m;

bool cuplaj (int nod) {
  for (int nn: g[nod])
    if (bip[nn] == 0) {
      bip[nod] = nn;
      bip[nn] = nod;
      return 1;
    }
  viz[nod] = 1;
  for (int nn: g[nod])
    if (viz[bip[nn]] == 0 && cuplaj(bip[nn]) == 1) {
      bip[nod] = nn;
      bip[nn] = nod;
      return 1;
    }
  return 0;
}

int main () {
  int e; fin >> n >> m >> e;
  int i, j, z, a, b;
  for (i = 1; i <= e; i++) {
    fin >> a >> b;
    g[a].pb(n+b);
    g[n+b].pb(a);
  }
  int aml = 1;
  while (aml) {
    aml = 0; fill(all(viz), 0);
    for (i = 1; i <= n; i++)
      if (bip[i] == 0) aml |= cuplaj(i);
  }
  int ans = 0;
  for (i = 1; i <= n; i++) ans += (bip[i] > 0);
  fout << ans << '\n';
  for (i = 1; i <= n; i++)
    if (bip[i] > 0) fout << i << ' ' << bip[i]-n << '\n';
  fin.close (); fout.close ();
  return 0;
}