#include <fstream>
using namespace std;

const int N=20003;
int cap[N][N],flux[N][N],T[N],v[N],n,m;
bool use[N];

ifstream in("cuplaj.in");
ofstream out("cuplaj.out");

bool bfs(int X,int Y)
{
	int st=0,dr=0,x,y;
	v[++dr]=X;
	for (x=0;x<=Y;x++)
	{
		use[x]=false;
		T[x]=0;
	}
	use[X]=true;
	while (st<dr)
	{
		x=v[++st];
		for (y=1;y<=Y;y++)
			if (!use[y] && flux[x][y]<cap[x][y])
			{
				v[++dr]=y;
				T[y]=x;
				use[y]=true;
			}
	}
	return use[Y];
}

int max_flow(int X,int Y)
{
	int M,i,j,flow=0;
	while (bfs(X,Y))
		for (i=1;i<Y;i++)
			if (flux[i][Y]<cap[i][Y])
			{
				M=cap[i][Y]-flux[i][Y];
				for (j=i;j!=X;j=T[j])
					M=min(M,cap[T[j]][j]-flux[T[j]][j]);
				if (!M)
					continue;
				T[Y]=i;
				for (j=Y;j!=X;j=T[j])
				{
					flux[T[j]][j]+=M;
					flux[j][T[j]]-=M;
				}
				flow+=M;
			}
	return flow;
}

int main()
{
	int i,j,k,x,y;
	in>>n>>m>>k;m+=n+1;
	while (k--)
	{
		in>>x>>y;
		cap[x][y]=1;
	}
	for (i=1;i<=n;i++)
		cap[0][i]=1;
	for (i=n+1;i<m;i++)
		cap[i][m]=1;
	out<<max_flow(0,m)<<"\n";
	for (i=1;i<=n;i++)
		for (j=n+1;j<m;j++)
			if (flux[i][j]==1)
				out<<i<<" "<<j<<"\n";
	return 0;
}