#include <cstdio>
#include <cstring>
#include <list>
#define pb push_back
using namespace std;

const int MAXN = 10010;
int n, m, cuplaj;
list<int> vecini[MAXN];	//tin doar vecinii nodurilor din stanga
int left[MAXN], right[MAXN], sel[MAXN];

void read();
void solve();
void write();
bool pairup(int);

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

bool pairup(int nod)
{
	if (sel[nod])
	{
		return 0;
	}
	sel[nod] = 1;
	list<int>::iterator it, sfarsit = vecini[nod].end();
	for (it = vecini[nod].begin(); it != sfarsit; ++it)
	{
		if (!right[*it])
		{
			right[*it] = nod;
			left[nod] = *it;
			return 1;
		}
	}
	for (it = vecini[nod].begin(); it != sfarsit; ++it)
	{
		if (pairup(right[*it]))
		{
			right[*it] = nod;
			left[nod] = *it;
			return 1;
		}
	}
	return 0;
}

void solve()
{
	cuplaj = 0;
	int i;
	list<int>::iterator it, sfarsit;
	int gasit = 1;
	while (gasit)
	{
		gasit = 0;
		memset(sel, 0, sizeof(sel));
		for (i = 1; i <= n; ++i)
		{
			if (!left[i])
			{
				gasit |= pairup(i);
			}
		}
	}
	for (i = 1; i <= n; ++i)
	{
		if (left[i])
		{
			++cuplaj;
		}
	}
}

void read()
{
	int i, e, x, y;
	FILE *fin = fopen("cuplaj.in", "r");
	fscanf(fin, "%d%d%d", &n, &m, &e);
	for (i = 1; i <= e; ++i)
	{
		fscanf(fin, "%d%d", &x, &y);
		vecini[x].pb(y);
	}
	fclose(fin);
}

void write()
{
	int i;
	FILE *fout = fopen("cuplaj.out", "w");
	fprintf(fout, "%d\n", cuplaj);
	for (i = 1; i <= n; ++i)
	{
		if (left[i])
		{
			fprintf(fout, "%d %d\n", i, left[i]);
		}
	}
	fclose(fout);
}