# include <fstream>
using namespace std;
struct nod {
	int info;
	nod *next;};
nod *g[10003];
int L[10003], R[10003], u[10003], cuplaj, n, m;

void read ()
{
	int e;
	nod *t;
	ifstream fin ("cuplaj.in");
	fin>>n>>m>>e;
	for (int i=1;i<=e;i++)
	{
		int i, j;
		fin>>i>>j;
		t=new nod;
		t->info=j;
		t->next=g[i];
		g[i]=t;
	}
}

int pereche (int x)
{
	int i;
	if (u[x])
		return 0;
	u[x]=1;
	for (nod *p=g[x]; p ;p=p->next)
	{
		i=p->info;
		if (R[i]==0 || pereche(R[i]))
		{
			L[x]=i;R[i]=x;
			return 1;
		}
	}
	return 0;
}

void cupleaza ()
{
	int gata=0;
	while (!gata)
	{
		gata=1;
		for (int i=1;i<=n;i++)
			u[i]=0;
		for (int i=1;i<=n;i++)
			if (L[i]==0)
				if (pereche(i))
				{
					cuplaj++;
					gata=0;
				}
	}
}

void write ()
{
	ofstream fout ("cuplaj.out");
	fout<<cuplaj<<endl;
	for (int i=1;i<=n;i++)
		if (L[i])
			fout<<i<<" "<<L[i]<<endl;
}

int main ()
{
	read ();
	cupleaza ();
	write ();
	return 0;
}