#include <stdio.h>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <vector>
using namespace std;
#define Max 100001

vector<int>g[10001];
int n,m,st[10001],dr[10001];

bool viz[10001];

bool dfs(int x)
{
	int y;
	if(viz[x])return 0;
	viz[x]=1;
	for(int i=0;i<g[x].size();i++)
	{
		y=g[x][i];
		if(st[y]==0 || dfs(y))
		{
			st[y]=x;
			dr[x]=y;
			return 1;
		}
	}
	return 0;
}

void cuplaj()
{
	int nr = 0,ok = 1;
	while(ok)
	{
		ok=0;
		memset(viz,0,sizeof(viz));
		for(int i=1;i<=n;i++)
			if(dr[i]==0 && dfs(i))
			{
				nr++;
				ok = 1;
			}
	}
	printf("%d\n",nr);
	for(int i=1;i<=n;i++)
		if(dr[i]!=0)printf("%d %d\n",i,dr[i]);
}

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