#include <fstream>
#include <vector>
using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
vector<short>g[10001];
vector<bool>vs;
short l[10001], r[10001];
int n, m, e, x, y;
bool Cuplare(int nod)
{
    if ( vs[nod] ) return 0;
    vs[nod] = 1;
    for ( vector<short>::iterator it = g[nod].begin(); it < g[nod].end(); ++it )
        if ( !r[*it] || Cuplare(r[*it]) )
        {
            r[*it] = nod;
            l[nod] = *it;
            return 1;
        }
    return 0;
}
void Solve()
{
    bool ok=1;
    int res=0;
    while ( ok )
    {
        vs.assign(n+1,0);
        ok=0;
        for ( int i = 1; i<= n; i++ )
            if ( !l[i] )
                if ( Cuplare(i) )
                    res++, ok=1;
    }
    fout << res << '\n';
    for ( int i = 1; i <= n; i++ )
        if ( l[i] )
            fout << i << ' ' << l[i] << '\n';
}
int main()
{
    fin >> n >> m >> e;
    while ( e-- )
    {
        fin >> x >> y;
        g[x].push_back(y);
    }
    Solve();
    fin.close();
    fout.close();
    return 0;
}