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

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

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

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);
	}
	for (i=1;i<=n;i++)
    {
        for (j=1;j<=n;j++)
            v[j]=0;
        ok=0;
        df(i);
    }
    g << nr << "\n";
    for (i=1;i<=m;i++)
        if (d[i]!=0)
            g << d[i] << ' ' << i << "\n";
    return 0;
}