#include<fstream>
#include<iostream>
#include<vector>
#include<cstring>
#define NMax 10005
using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");

int N,M,E,Sol;
int R[NMax],L[NMax];
bool Ok = 1,Use[NMax];

vector <int> G[NMax];

void Read()
{
    fin>>N>>M>>E;

    for(int i = 1 ; i <= E ; ++i)
    {
        int x,y;    fin>>x>>y;
        G[x].push_back(y);
    }
}

bool PairUp(int Nod)
{
    if(Use[Nod])    return 0;

    Use[Nod] = 1;

    for(int i = 0 ; i < (int) G[Nod].size() ; ++i)
    {
        int Vecin = G[Nod][i];
        if(!R[Vecin])
        {
            L[Nod] = Vecin;
            R[Vecin] = Nod;
            return 1;
        }
    }

    for(int i = 0 ; i < (int) G[Nod].size() ; ++i)
    {
        int Vecin = G[Nod][i];
        if(PairUp(R[Vecin]))
        {
            L[Nod] = Vecin;
            R[Vecin] = Nod;
            return 1;
        }
    }

    return 0;
}

void Solve()
{
    do
    {
        Sol = Ok = 0;

        memset(Use,0,sizeof(Use));

        for(int i = 1 ; i <= N ; ++i)
            if(!L[i])
                Ok = Ok | PairUp(i);
            else Sol++;
    }while(Ok);
}

void Print()
{
    fout<<Sol<<"\n";

    for(int i = 1 ; i <= N ; ++i)
        if(L[i])
            fout<<i<<" "<<L[i]<<"\n";
}

int main()
{
    Read();
    Solve();
    Print();

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