#include <bits/stdc++.h>
#define pp pair<int,int>
#define x first
#define y second
using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
int i,j,n,m,fiu[10001],parinte[10001];
bool fv[10001];
vector<int> v[10001];
bool go(int nod)
{
    if(fv[nod])
        return 0;
    fv[nod] = 1;
    for(int i = 0 ; i < v[nod].size(); i++)
        if(parinte[ v[nod][i] ] == 0)
        {
            parinte[ v[nod][i] ] = nod;
            fiu[ nod ] = v[nod][i];
            return 1;
        }
    for(int i = 0 ; i < v[nod].size(); i++)
        if( go( parinte[ v[nod][i] ] ) )
        {
            parinte[ v[nod][i] ] = nod;
            fiu[ nod ] = v[nod][i];
            return 1;
        }
    return 0;
}
int main()
{
    fin >> n >> m >> m;
    for(i = 1; i <= m; i++)
    {
        int a,b;
        fin >> a >> b;
        v[a].push_back(b);
    }
    for(i = 1; i <= n; i++)
        if( go(i) )
        {
            memset(fv,0,sizeof(fv));
            j++;
        }
    fout<<j<<'\n';
    for(i = 1; i <= n; i++)
        if(fiu[i])
            fout<<i<<" "<<fiu[i]<<'\n';
    return 0;
}