#include <fstream>
#include <vector>
#include <cstring>

using namespace std;

ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");

vector<int> V[10001];
bool used[10001];
int L[10001],R[10001];


bool cuplaj(int nod)
{
    if(used[nod])
        return false;
    used[nod] = true;
    for(vector<int>::iterator it = V[nod].begin(); it != V[nod].end() ;it++)
        if(!R[*it] || cuplaj(R[*it]) )
        {
            R[*it] = nod;
            L[nod] = *it;
            return true;
        }
    return false;
}

int main()
{
    int n,m,e,x,y;
    fin>>n>>m>>e;
    for(int i = 1; i <= e; i++)
    {
        fin >> x >> y;
        V[x].push_back(y);
    }
    int sol = 0;
    bool ok = true;
    while(ok)
    {
        ok = false;
        memset(used,false,sizeof(used));
        for(int i=1;i<=n;i++)
            if(!L[i] && cuplaj(i))
            {
                ok = true;
                sol++;
            }
    }
    fout<<sol<<'\n';
    for(int i=1;i<=n;i++)
        if(L[i])
            fout<<i<<' '<<L[i]<<'\n';

    fin.close();
    fout.close();
    return 0;
}