#include <iostream>
#include <fstream>
#include <vector>
using namespace std;

vector<int> a[10001],b[10001];
int d[10001],v[10001],w[10001],i,n,m,k,x,y,nr,j,ok,t;

void df(int x)
{
    int i,y;
	v[x]=1;
    for (i=0;i<a[x].size();i++)
    {
        y=a[x][i];
        if (d[y]==0)
        {
            ok=1;
            d[y]=x;
            nr++;
			break;
        }
        else if (v[d[y]]==0)
        {
			df(d[y]);
			if (ok==1)
            {
				d[y]=x;
				break;
			}
        }
    }
}

int main()
{
    ifstream f("cuplaj.in");
	ofstream g("cuplaj.out");
	f >> n >> m >> k;
	for (i=1;i<=k;i++)
	{
        f >> x >> y;
        a[x].push_back(y);
        b[y].push_back(x);
	}
	t=1;
	while (t)
    {
        t=0;
		for (i=1;i<=n;i++)
            v[i]=0;
		for (i=1;i<=n;i++)
			if (w[i]==0)
			{
				ok=0;
				df(i);
				if (ok==1)
				{
					t=1;
					w[i]=1;
				}
			}
		}
    g << nr << "\n";
    for (i=1;i<=m;i++)
        if (d[i]!=0)
            g << d[i] << ' ' << i << "\n";
    return 0;
}