#include<iostream>
#include<fstream>
#include<vector>
using namespace std;
vector <int> v[10001];
int viz[10001],numar,n,m,e,i,j,x,y,stanga[10001],dreapta[10001],ok;
int pair_up(int nod)
{
  viz[nod]=1;
  for(int i=0;i<v[nod].size();i++)
  {
      if(stanga[v[nod][i]]==0)
      {
          dreapta[nod]=v[nod][i];
          stanga[v[nod][i]]=nod;
          return 1;
      }
      if(viz[stanga[v[nod][i]]]==0)
        if(pair_up(stanga[v[nod][i]])==1)
        {
            stanga[v[nod][i]]=nod;
            dreapta[nod]=v[nod][i];
            return 1;
        }
  }
  return 0;
}

int main()
{
    ifstream f("cuplaj.in");
    ofstream g("cuplaj.out");
    f>>n>>m>>e;

    for(i=1;i<=e;i++)
    {
        f>>x>>y;
        v[x].push_back(y);
    }
ok=1;numar=0;
    while(ok==1)
    {
        ok=0;
        for(j=1;j<=n;j++) viz[j]=0;

        for(j=1;j<=n;j++)
            if(dreapta[j]==0)
                if(viz[j]==0)
                    ok=pair_up(j);
    }
    for(i=1;i<=m;i++)
        if(stanga[i]!=0) numar++;

    g<<numar<<"\n";
    for(i=1;i<=m;i++)
        g<<stanga[i]<<" "<<i<<"\n";

    return 0;
}