#include <cstdio>
#include <vector>
#include <cstring>
using namespace std;
#define N 10001
int n,m,e,draw,sol;
vector <int> a[N];
int g[N];
int u[N],mark[N],c[N];

int DFS(int nod)
{
	if (u[nod]==draw)
        return 0;
	u[nod]=draw;
	for(int i=0;i<g[nod];++i)
		if(mark[a[nod][i]]==-1||DFS(mark[a[nod][i]]))
		{
			c[nod]=a[nod][i];
			mark[a[nod][i]]=nod;
			return 1;
		}
	return 0;
}

void cuplaj()
{
	memset(mark,-1,sizeof(mark));
	int last=-1,i;
	while (last!=sol)
	{
		last=sol;
		++draw;
		for(i=1;i<=n;++i)
			if(!c[i])
                sol+=DFS(i);
	}
}

int main()
{
	freopen("cuplaj.in","r",stdin);
	freopen("cuplaj.out","w",stdout);
	int i,x,y;
	scanf("%d %d %d ",&n,&m,&e);
	for(i=1;i<=e;++i)
		scanf("%d %d ",&x,&y),a[x].push_back(y);
	for(i=1;i<=n;++i)
        g[i]=a[i].size();
	cuplaj();
	printf("%d\n",sol);
	for(i=1;i<=n;++i)
		if(c[i]) printf("%d %d\n",i,c[i]);
	return 0;
}