#include<vector>
#include<stdio.h>
using namespace std;
#define DIM 10005
int st[DIM],dr[DIM];
int n,m,e,x,y,Rez;
vector <int> g[DIM];
vector <bool> ut;
int cuplaj(int nod)
{
	if(ut[nod])
		return 0;
	ut[nod]=1;
	vector <int> ::iterator it;
	for(it=g[nod].begin();it!=g[nod].end();it++)
	{
		if(dr[*it]==0)
		{
			st[nod]=*it;
				dr[*it]=nod;
				return 1;
		}
		else
			if(cuplaj(dr[*it]))
			{
				st[nod]=*it;
				dr[*it]=nod;
				return 1;
			}
	}
	return 0;
}
int main()
{
	freopen("cuplaj.in","r",stdin);
	freopen("cuplaj.out","w",stdout);
	scanf("%d%d%d",&n,&m,&e);
	for(int i=1;i<=e;i++)
	{
		scanf("%d%d",&x,&y);
		g[x].push_back(y);
	}
	while(1)
	{
		ut.clear();ut.resize(n+m,0);
		for(int i=1;i<=n;i++)
			if(!st[i])
				if(cuplaj(i))
					Rez++,ut[0]=1;
		if(ut[0]==0)
			break;
	}
	printf("%d\n",Rez);
	for(int i=1;i<=n;i++)
		if(st[i])
			printf("%d %d\n",i,st[i]);
	return 0;
}