#include <stdio.h>
#include <string.h>
#include <vector>
#define NMAX 10005
#define pb push_back
using namespace std;
int n,m,r,st[NMAX],dr[NMAX],rez;
vector <int> A[NMAX];
char marc[NMAX];
void read()
{
	scanf("%d%d%d",&n,&m,&r);
	int i,a,b;
	for (i=1; i<=r; i++)
	{
		scanf("%d%d",&a,&b);
		A[a].pb(b);
	}
}
int choice(int nod)
{
	marc[nod]=1;
	int i,vec;
	for (i=0; i<A[nod].size(); i++)
	{
		vec=A[nod][i];
		if (!dr[vec])
		{
			st[nod]=vec;
			dr[vec]=nod;
			return 1;
		}
	}
	for (i=0; i<A[nod].size(); i++)
	{
		vec=A[nod][i];
		if (!marc[dr[vec]] && choice(dr[vec]))
		{
			st[nod]=vec;
			dr[vec]=nod;
			return 1;
		}
	}
	return 0;
}
void solve()
{
	int i,fin=1;
	while (fin)
	{
		memset(marc,0,sizeof(marc));
		fin=0;
		for (i=1; i<=n; i++)
			if (!st[i])
			{
				if (choice(i))
					rez++,fin=1;
			}
	}
	printf("%d\n",rez);
	for (i=1; i<=n; i++)
		if (st[i])
			printf("%d %d\n",i,st[i]);
}
int main()
{
	freopen("cuplaj.in","r",stdin);
	freopen("cuplaj.out","w",stdout);
	read();
	solve();
	return 0;
}