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

vector <int> v[10009];


int st[10009],dr[10009],da[10009];

int cuplare(int nod,int ord)
{
	int ok=0;
	if (da[nod]==ord) return 0;
	da[nod]=ord;
	for (vector<int>::iterator it=v[nod].begin();it!=v[nod].end();++it)
		if (!dr[*it])
			{st[nod]=*it,dr[*it]=nod,ok=1; break;}
	if (!ok)
		for (vector<int>::iterator it=v[nod].begin();it!=v[nod].end();++it)
			if (cuplare(dr[*it],ord))
				{st[nod]=*it,dr[*it]=nod,ok=1; break;}
	return ok;			
}
	
		
		

int main()
{
	int n,m,e,i,x,y,rez=0,k=1;
	
	freopen("cuplaj.in","r",stdin);
	freopen("cuplaj.out","w",stdout);
	scanf("%d %d %d",&n,&m,&e);
	for (i=1;i<=e;++i)
	{
		scanf("%d %d",&x,&y);
		v[x].pb(y);
	}
	for (i=1;i<=n;++i)
		if (cuplare(i,k))
			++rez; else
				++k,rez+=cuplare(i,k);
			
	printf("%d\n",rez);
	for (i=1;i<=n;++i)
		if (st[i])
			printf("%d %d\n",i,st[i]);
	return 0;
}