#include <fstream>
#include <vector>
#include <bitset>
#define x first
#define y second
#define mp make_pair
using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
int i,j,n,m,a,b,c,nod,cuplaj,s[10005],d[10005];
vector <int > v[10005];
bitset<10001> f;
bool cuplare(int nod)
{
    int j;
    if(f[nod])
        return 0;
    f[nod] = 1;
    for(j = 0; j < v[nod].size(); j++)
        if(s[ v[nod][j] ] == 0)
        {
            s[ v[nod][j] ] = nod;
            d[nod] = v[nod][j];
            return 1;
        }
    for(j = 0; j < v[nod].size(); j++)
        if( cuplare(s[ v[nod][j] ]) )
        {
            s[ v[nod][j] ] = nod;
            d[nod] = v[nod][j];
            return 1;
        }
    return 0;

}
int main()
{
    fin >> n >> m >> m;
    for(i = 1; i <= m; i++)
    {
        fin >> a >> b;
        v[a].push_back(b);
    }
    for(i = 1; i <= n; i++)
        if(!d[i]&&cuplare(i))  cuplaj++,f=0;

    fout<<cuplaj<<'\n';

    for(i = 1; i <= n; i++)
        if(d[i])
            fout<<i<<" "<<d[i]<<'\n';
    return 0;
}