#include<bits/stdc++.h>
#define ull unsigned long long
#define ui unsigned int
#define ld long double
#define ll long long
#define lll __int128
#define fi first
#define se second
#define e emplace
#define eb emplace_back
#define db double
#define ef emplace_front
#define pii pair<int,int>
#define pll pair<ll,ll>
#define vi vector<int>
#define vp vector<pii>
#define mp make_pair

//#define LOCALJUDGE
#define int ll
bool ST;
static const ll MOD=998244353,Phi=998244352,inv2=499122177,Root=3,iRoot=332748118;
static const ll inf=1073741823,INF=4557430888798830399;
static const double eps=1e-8,pi=3.1415926535;
char in[1<<20],*p1=in,*p2=in;
using namespace std;
// #define getchar() (p1==p2&&(p2=(p1=in)+fread(in,1,1<<20,stdin),p1==p2)?EOF:*p1++)
struct tup{int x,y,z;tup(int X=0,int Y=0,int Z=0){x=X,y=Y,z=Z;}};
namespace FastIO
{
	template<typename T> inline void write(T x,char ch=' ')
	{
		if(is_same<char,T>::value)putchar(x);
		else
		{
			if(x<0)x=-x,putchar('-');

			static char st[50];int top=0;
			do{st[top++]=x%10+'0',x/=10;}while(x);
			while(top)putchar(st[--top]);
		}
		ch!='~'?putchar(ch):0;
	}
	inline void write(const char*x,char ch=' ')
	{
		for(int i=0;x[i]!='\0';++i)putchar(x[i]);
		ch!='~'?putchar(ch):0;
	}
	inline void read(char&s){do s=getchar();while(s=='\n'||s==' ');}
	inline void read(char s[])
	{
		int len=0;char st;
		do st=getchar();while(st=='\n'||st==' ');
		s[++len]=st,st=getchar();
		while(st!='\n'&&st!=' ')s[++len]=st,st=getchar();
		s[++len]='\0';
	}
	template<typename T> inline void read(T &s)
	{
		s=0;char ch=getchar();
		while((ch>'9'||ch<'0')&&ch!='-')ch=getchar();
		bool tf=(ch=='-')&&(ch=getchar());
		while((ch>='0')&&(ch<='9'))s=(s<<1)+(s<<3)+ch-'0',ch=getchar();
		s=(tf?-s:s);
	}
	template<typename T1,typename T2> inline void read(pair<T1,T2> &s){read(s.fi),read(s.se);}
	template<typename T,typename...Args> inline void write(T x,Args...args){write(x,'~'),write(args...);}
	template<typename T,typename...Args> inline void read(T&x,Args&...args){read(x),read(args...);}
}
using namespace FastIO;
namespace MTool
{
	inline int Cadd(int a,int b){return (ll)a+b>=MOD?(ll)a+b-MOD:a+b;}
	inline int Cdel(int a,int b){return a-b<0?a-b+MOD:a-b;}
	inline int Cmul(int a,int b){return 1ll*a*b%MOD;}
	inline int sqr(int a){return 1ll*a*a%MOD;}
	inline void Madd(int&a,int b){a=((ll)a+b>=MOD?(ll)a+b-MOD:a+b);}
	inline void Mdel(int&a,int b){a=(a-b<0?a-b+MOD:a-b);}
	inline void Mmul(int&a,int b){a=1ll*a*b%MOD;}
	template<typename T> inline bool Mmax(T&a,T b){return a<b?a=b,1:0;}
	template<typename T> inline bool Mmin(T&a,T b){return a>b?a=b,1:0;}
	template<typename...Args> inline void Madd(int&a,int b,Args...args){Madd(a,b),Madd(a,args...);}
	template<typename...Args> inline void Mmul(int&a,int b,Args...args){Mmul(a,b),Mmul(a,args...);}
	template<typename...Args> inline void Mdel(int&a,int b,Args...args){Mdel(a,b),Mdel(a,args...);}
	template<typename...Args> inline int Cadd(int a,int b,Args...args){return Cadd(Cadd(a,b),args...);}
	template<typename...Args> inline int Cmul(int a,int b,Args...args){return Cmul(Cmul(a,b),args...);}
	template<typename...Args> inline int Cdel(int a,int b,Args...args){return Cdel(Cdel(a,b),args...);}
	template<typename...Args,typename T> inline bool Mmax(T&a,T b,Args...args){return Mmax(a,b)|Mmax(a,args...);}
	template<typename...Args,typename T> inline bool Mmin(T&a,T b,Args...args){return Mmin(a,b)|Mmin(a,args...);}
	inline int power(int x,int y){int s=1;for(;y;y>>=1,Mmul(x,x))if(y&1)Mmul(s,x);return s;}
}
using namespace MTool;
namespace WrongAnswer_90
{
	int cnt,L,R,m,S,T,head[200010],to[800010],v[800010],nex[800010],now[200010],d[200010];
	inline void Add(int x,int y,int z){to[++cnt]=y,nex[cnt]=head[x],head[x]=cnt,v[cnt]=z;}
	inline void add(int x,int y,int z){Add(x,y,z),Add(y,x,0);}
	inline bool bfs()
	{
		queue<int> q;q.e(S),memset(d,0,sizeof(d)),d[S]=1,now[S]=head[S];
		while(!q.empty())
		{
			int nw=q.front();q.pop();
			for(int i=head[nw];i;i=nex[i])
			{
				if(v[i]&&!d[to[i]])
				{
					d[to[i]]=d[nw]+1,now[to[i]]=head[to[i]],q.e(to[i]);
					if(to[i]==T)return 1;
				}
			}
		}
		return 0;
	}
	int dinic(int x,int flow)
	{
		if(x==T)return flow;
		int rest=flow,t;
		for(int i=now[x];i&&rest;i=nex[i])
		{
			now[x]=i;
			if(!v[i]||d[to[i]]!=d[x]+1)continue;
			t=dinic(to[i],min(rest,v[i]));
			v[i]-=t,v[i^1]+=t,rest-=t;
			if(!t)d[to[i]]=0;
		}
		return flow-rest;
	}
	inline void mian()
	{
		read(L,R,m),S=L+R+1,T=S+1;int x,y,s=0;
		while(m--)read(x,y),add(x+1,y+1+L,1);
		for(int i=1;i<=L;++i)add(S,i,1);
		for(int i=L+1;i<=L+R;++i)add(i,T,1);
		while(bfs())while((x=dinic(S,INF)))s+=x;
		write(s,'\n');
		for(int i=head[S];i;i=nex[i])
		{
			if(!v[i])
			{
				int s=0;
				for(int j=head[to[i]];j;j=nex[j])
				if(!v[j]){++s;write(to[i]-1,' ',to[j]-L-1,'\n');}
				assert(s==1);
			}
		}
	}
}
bool ED;
signed main()
{
	#ifdef LOCALJUDGE
	freopen("ex_mod5.in","r",stdin);
	freopen("1.out","w",stdout);
	#endif
	double st=clock();
	WrongAnswer_90::mian();
	double ed=clock();
	#ifndef LOCALJUDGE
 	cerr<<endl;
	#endif
 	cerr<<"Time: "<<ed-st<<" ms\n";
	#ifdef LOCALJUDGE
 	cerr<<"     ";
	#endif
 	cerr<<"Memory: "<<abs(&ST-&ED)/1024.0/1024.0<<" MB\n";
	return 0;
}