#include <cstdio>
#include <vector>
#include <cstring>
using namespace std;

const int MAX_N = 10100;

int n, m, e, sol;
int f[MAX_N], c[MAX_N], c2[MAX_N];
vector <int> v[MAX_N];

int cuplaj(int nod)
{
	if (f[nod]) return 0;
	f[nod] = 1;

	for (vector <int>::iterator it = v[nod].begin(); it != v[nod].end(); ++it)
		if (!c[*it])
		{
			c[*it] = nod;
			c2[nod] = 1;
			return 1;
		}
		else if (c[*it] != nod && cuplaj(c[*it]))
		{
			c[*it] = nod;
			c2[nod] = 1;
			return 1;
		}
	return 0;
}

int main()
{
	int i, x, y;
	freopen("cuplaj.in", "r", stdin);
	freopen("cuplaj.out", "w", stdout);

	scanf("%d %d %d", &n, &m, &e);

	for (i = 1; i <= e; ++i)
	{
		scanf("%d %d", &x, &y);
		v[x].push_back(y);
	}

	int ok = 1;

	while (ok)
	{
		ok = 0;

		memset(f, 0, sizeof(f));
		for (i = 1; i <= n; ++i) 
		{
			int q = (c2[i]) ? 0 : cuplaj(i);

			sol += q;
			ok |= q;
		}
	}

	printf("%d\n", sol);
	
	for (i = 1; i <= n; ++i) 
		if (c[i]) printf("%d %d\n", c[i], i);
}