#include<bits/stdc++.h>
#pragma GCC optimize(2)
using namespace std;
inline int read()
{
	int n=0,f=1,ch=getchar();
	while(ch<'0'||ch>'9')
	{
		if(ch=='-')f=-1;
		ch=getchar();
	}
	while(ch>='0'&&ch<='9')
	{
		n=n*10+ch-'0';
		ch=getchar();
	}
	return n*f;
}
int n,m,s,t;
struct bbian
{
	int u,v,w,nex;
}a[1600004];
int head[400005],tmp=1;
void addb(int x,int y,int z)
{
	a[++tmp].u=x;
	a[tmp].v=y;
	a[tmp].w=z;
	a[tmp].nex=head[x];
	head[x]=tmp;
}
int dis[400005];
queue<int>que;
bool bfs()
{
	for(int i=1;i<=t;i++)dis[i]=1000000000;
	dis[s]=0;
	que.push(s);
	while(!que.empty())
	{
		int x=que.front();
		que.pop();
		for(int i=head[x];i;i=a[i].nex)
		{
			if(a[i].w==0)continue;
			if(dis[a[i].v]>dis[x]+1)
			{
				dis[a[i].v]=dis[x]+1;
				que.push(a[i].v);
			}
		}
	}
	if(dis[t]==1000000000)return false;
	return true;
}
int cur[400005];
int dfs(int x,int rf)
{
	if(rf==0)return 0;
	if(x==t)return rf;
	int ans=0;
	for(int i=head[x];i;i=a[i].nex)
	{
		if(dis[a[i].v]!=dis[x]+1||a[i].w==0)continue;
		int sth=dfs(a[i].v,min(rf,a[i].w));
		if(sth==0)
		{
			dis[a[i].v]=1000000000;
			continue;
		}
		a[i].w-=sth;
		a[i^1].w+=sth;
		ans+=sth;
		rf-=sth; 
		if(!rf)break;
	}
	return ans;
}
int bu[500005],bv[500005],p[500005];
mt19937 ran(121296);
signed main()
{
	int l,r,m;
	l=read();
	r=read();
	m=read();
	s=l+r+1;
	t=l+r+2; 
	int x,y,z;
	for(int i=1;i<=m;i++)
	{
		bu[i]=read();
		bv[i]=read();
		p[i]=i;
	}
	shuffle(p+1,p+n+1,ran);
	for(int i=1;i<=m;i++)
	{
		x=bu[p[i]]+1;
		y=bv[p[i]]+l+1;
		addb(x,y,1);
		addb(y,x,0);
	}
	for(int i=1;i<=l;i++)addb(s,i,1),addb(i,s,0);
	for(int i=l+1;i<=l+r;i++)addb(i,t,1),addb(t,i,0);
	int ans=0;
	while(bfs())
	{
		ans+=dfs(s,1000000000);
	}
	printf("%d\n",ans);
	for(int i=1;i<=m;i++)
	{
		//printf("%lld %lld\n",a[2*i].u,a[2*i].v);
		if(a[2*i].w==0)printf("%d %d\n",a[2*i].u-1,a[2*i].v-l-1);
	}
	return 0;
}