#include <fstream>
#include <vector>
using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
int n,m,E,j,R,st[10005],dr[10005],ok;
vector <int>v[10005];
bool viz[10005];
bool Cuplaj(int x)
     {int i,y;
      if(viz[x])return 0;
      viz[x]=1;
      for(i=0;i<v[x].size();i++)
         {y=v[x][i];
          if(dr[y]==0)
             {st[x]=y;
              dr[y]=x;
              return 1;
             }
         }
      for(i=0;i<v[x].size();i++)
         {y=v[x][i];
          if(Cuplaj(dr[y]))
             {st[x]=y;
              dr[y]=x;
              return 1;
             }
         }
         return 0;
     }
int main()
{int x,y,i;
 fin>>n>>m>>E;
 for(i=1;i<=E;i++)
    {fin>>x>>y;
     v[x].push_back(y);
    }
 while(ok==0)
      {ok=1;
       for(i=1;i<=n;i++)
          viz[i]=0;
       for(i=1;i<=n;i++)
          {if(dr[i]==0&&Cuplaj(i)){R++;ok=0;}
          }
      }
 fout<<R<<"\n";
 for(i=1;i<=n;i++)
    if(st[i])fout<<i<<" "<<st[i]<<"\n";
}