#include<stdio.h>
using namespace std;
int n,m,e,l[10005],r[10005],viz[10005];

struct nod
{
	int x;
	nod *adresa;
};
nod *a[10005];

void adaug(int x,int y)
{
	nod *p;
	p=new nod;
	p->x=y;
	p->adresa=a[x];
	a[x]=p;
}

void citire()
{
	int i,x,y;
	scanf("%d %d %d",&n,&m,&e);
	for(i=1;i<=n+m;i++)
		a[i]=0;
	for(i=1;i<=e;i++)
	{
		scanf("%d %d",&x,&y);
		adaug(x,y);
	}
}

int cuplaj(int x)
{
	nod *p;
	if(viz[x])
		return 0;
	viz[x]=1;
	for(p=a[x];p!=0;p=p->adresa)
		if(!r[p->x])
		{
			l[x]=p->x;
			r[p->x]=x;
			return 1;
		}
	for(p=a[x];p!=0;p=p->adresa)
		if(cuplaj(r[p->x]))
		{
			l[x]=p->x;
			r[p->x]=x;
			return 1;
		}
	return 0;
}

void scrie()
{
	int c,i;
	c=0;
	for(i=1;i<=n;i++)
		if(l[i])
			c++;
	printf("%d\n",c);
	for(i=1;i<=n;i++)
		if(l[i])
			printf("%d %d\n",i,l[i]);
}

int main()
{
	int i,ok;
	freopen("cuplaj.in","r",stdin);
	freopen("cuplaj.out","w",stdout);
	citire();
	ok=1;
	while(ok)
	{
		ok=0;
		for(i=1;i<=n;i++)
			viz[i]=0;
		for(i=1;i<=n;i++)
			if(!l[i])
				ok=ok+cuplaj(i);
	}
	scrie();
	return 0;
}