#include<iostream>
#include<fstream>

using namespace std;

int a[10000][10000],cuplaj[10000],viz[10000];
int i,j,n,m,card,e,k;

int cupleaza(int i)
{
	int j;
	if(viz[i] == 1)
		return 0;
	viz[i] = 1;
	
	for(j=1;j<=n;j++)
		if((a[i][j] == 1 && (cuplaj[j] !=i || cupleaza(cuplaj[j]) == 1)) )
		{
			cuplaj[j] = i;
			return 1;
		}
	return 0;
}


int main()
{
	
	ifstream fin("cuplaj.in");
	ofstream fout("cuplaj.out");
	
	fin>>n>>m>>e;
	
	for(k=1;k<=e;k++)
	{
		fin>>i>>j;
		a[i][j] = 1;
	}
	
	for(i=1;i<=n;i++)
	{
		for(j=1;j<=n;j++)
			viz[j] = 0;
	card = card + cupleaza(i);
	}
	
	fout<<card<<"\n";
	
	for(j=1;j<=card;j++)
		if(cuplaj[j])
			fout<<cuplaj[j]<<" "<<j<<"\n";
			
return 0;
}