#include<fstream>
#include<cstdio>
#include<set>
#include<vector>
#include<algorithm>
#define FOR(a,b,c) for(int a=b;a<=c;++a)
#include<cstring>
#include<bitset>
#include<cmath>
#include<iomanip>
#include<queue>
#define f cin
#define g cout
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define ll unsigned long long
#define bit 20
#define inf 500000000
#define base 256
#define ba 255
#define N 10100
#define mod  1999999973
#define inu "cuplaj.in"
#define outu "cuplaj.out"
using namespace std;
ifstream f(inu);
ofstream g(outu);
//int dx[]={0,0,0,1,-1};
//int dy[]={0,1,-1,0,0};
vector<int> v[N];
int l[N],r[N],viz[N],n,c,edge,m,x,y,OK;
int cuplaj(int x)
{
	if(viz[x])
		return 0;
	for(int i=0;i<v[x].size();++i)
		if(!r[v[x][i]])
		{
			l[x]=v[x][i];
			r[v[x][i]]=x;
			return 1;
		}
	for(int i=0;i<v[x].size();++i)
		if(cuplaj(r[v[x][i]]))
		{
			l[x]=v[x][i];
			r[v[x][i]]=x;
			return 1;
		}
	return 0;
}
int main ()
{
	f>>n>>m>>edge;
	FOR(i,1,edge)
	{
		f>>x>>y;
		v[x].push_back(y);
	}
	OK=1;
	while(OK)
	{
		memset(viz,0,sizeof(viz));
		OK=0;
		FOR(i,1,n)
			if(!l[i])
			if(cuplaj(i))
			{
				OK=1;
				c++;
			}
	}
	g<<c<<"\n";
	FOR(i,1,n)
	if(l[i])
		g<<i<<" "<<l[i]<<"\n";
	return 0;
}