#include <fstream>
#include <cstring>
#define nmax 10005

using namespace std;

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

int uz[nmax], st[nmax], dr[nmax];
int n, m, e, nr, sup, a, b;

struct lista
{
	int inf;
	lista * nod;
} * g[nmax];

void add(int i, int j)
{
	lista * p;
	p = new lista;
	p -> inf = j;
	p -> nod = g[i];
	g[i] = p;
}

int cuplaj(int nod)
{
	lista * p;
	if(uz[nod]) return 0;
	uz[nod] = 1;
	for(p = g[nod]; p; p = p->nod)
		if(!dr[p->inf] || cuplaj(dr[p->inf]))
		{
			st[nod] = p->inf;
			dr[p->inf] = nod;
			return 1;
		}
	return 0;
}

int main()
{
	int i;
	fin >> n >> m >> e;
	for(i = 1; i <= e; ++ i)
	{
		fin >> a >> b;
		add(a, b);
	}
	sup = 1;
	for(i = 1; i <= n; ++ i)
	{
		if(st[i]) continue;
		if(cuplaj(i)) ++ nr;
		else
		{
			memset(uz, 0, sizeof(uz));
			if(cuplaj(i)) ++ nr;
		}
	}
	fout << nr << "\n";
	for(i = 1; i <= n; ++ i)
		if(st[i] )
			fout << i << " " << st[i] << "\n";
	return 0;
}