#include <stdio.h>
#include <vector>
#define Nmax 10002
#define pb push_back
using namespace std;

vector< int > V[Nmax];
int L[Nmax],R[Nmax];
int use[Nmax];
int n,m,e,nr;

int cuplez(int i){
	vector< int >:: iterator it;
	use[i]=1;
	for(it=V[i].begin(); it!=V[i].end(); ++it)
		if( !R[*it] || ( !use[R[*it]] && cuplez(R[*it]) ) ){
			L[i]=*it; R[*it]=i;
			return 1;
		}
	return 0;
}

void cuplaj(){
	int i,done=0;
	while( !done ){
		done=1;
		memset(use,0,sizeof(use));
		for(i=1;i<=n;++i)
			if( !L[i] && cuplez(i) ){
				++nr;
				done=0;
			}
	}
}

int main(){
	int i,x,y;
	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);
	}
	
	cuplaj();
	
	printf("%d\n",nr);
	for(i=1;i<=n;++i)
		if(L[i]) printf("%d %d\n",i,L[i]);
	
	fclose(stdin); fclose(stdout);
	return 0;
}