#include <fstream>
#include <vector>
#include <cstring>
#include <bitset>
using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
#define dim 100005
vector <int> v[dim];
int level[dim],r[dim],n ,m, e,nrt;
int viz[dim];

void read()
{
	int x, y, i;
	fin>>n >>m >>e;
	for(i=1;i<=e;++i)
	{
		fin>>x >>y;
		v[x].push_back(y);
	}
}

int pairup(int nod)
{
	if(viz[nod]==1)
		return 0;
	viz[nod]=1;
	
	for(int k=0;k<(int)v[nod].size();++k)
		if(!r[v[nod][k]])
		{
			level[nod]=v[nod][k];
			r[v[nod][k]]=nod;
			return 1;
		}
	
	for(int k=0;k<(int)v[nod].size();++k)
		if(pairup(r[v[nod][k]]))
		{
			level[nod]=v[nod][k];
			r[v[nod][k]]=nod;
			return 1;
		}
		
	return 0;
}

void solve()
{
	int i, ok;
	
	do
	{
		ok=0;
		memset(viz,0,sizeof(viz));
		for(i=1;i<=n;++i)
			if(!level[i] && pairup(i))
			{
				ok=1;
				++nrt;
			}
	}while(ok);
}

void print()
{
	fout<<nrt<<'\n';
	for(int i=1;i<=n;++i)
		if(level[i]!=0)
			fout<<i <<" " <<level[i] <<'\n';
}

int main()
{
	read();
	solve();
	print();
	return 0;
}