#include <fstream>
#include <vector>

using namespace std;

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

const int VAL = 10005;

int N, M, E, i, j;
int A, B, ANS;
int Left[VAL], Right[VAL];
vector <int> G[VAL], SOL;
bool gas, tried[VAL];

bool PairUp(int nod)
{
    if (tried[nod]==true)
        return false;
    tried[nod]=true;
    vector <int> :: iterator it;
    for (it=G[nod].begin(); it!=G[nod].end(); it++)
    {
        if (Left[*it]==0)
        {
            Left[*it]=nod;
            Right[nod]=*it;
            return true;
        }
    }
    for (it=G[nod].begin(); it!=G[nod].end(); it++)
    {
        if (PairUp(Left[*it])==true)
        {
            Left[*it]=nod;
            Right[nod]=*it;
            return true;
        }
    }
    return false;
}

int main()
{
    fin >> N >> M >> E;
    for (i=1; i<=E; i++)
    {
        fin >> A >> B;
        G[A].push_back(B);
    }
    while (1)
    {
        gas=false;
        for (i=1; i<=N; i++)
            tried[i]=false;
        for (i=1; i<=N; i++)
            if (Right[i]==0 && PairUp(i)==true)
                gas=true;
        if (gas==false)
            break;
    }
    for (i=1; i<=N; i++)
        if (Right[i]>0)
            SOL.push_back(i);
    fout << SOL.size() << '\n';
    for (i=0; i<SOL.size(); i++)
        fout << SOL[i] << " " << Right[SOL[i]] << '\n';
    fin.close();
    fout.close();
    return 0;
}