#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <cstring>

using namespace std;

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

const int N = 10005;

int n,m,e,L[N],R[N],cp;

bool seen[N];

vector <int> G[N];

void Read()
{
    fin>>n>>m>>e;
    while(e--)
        {
            int x,y;
            fin>>x>>y;
            G[x].push_back(y);
        }
}

int PairUP(int x)
{
    if(seen[x])
        return 0;
    seen[x]=1;
    vector <int> ::iterator it;
    for(it=G[x].begin(); it!=G[x].end(); it++)
        {
            if(!R[*it] || PairUP(R[*it]))
                {
                    L[x]=*it;
                    R[*it]=x;
                    return 1;
                }
        }
    return 0;
}

void Cuplaj()
{
    int ok=1;
    while(ok)
        {
            memset(seen,0,sizeof(bool)*(n+1));
            ok=0;
            for(int i=1; i<=n; i++)
                {
                    if(!L[i])
                        {
                            if(PairUP(i))
                                {
                                    cp++;
                                    ok=1;
                                }
                        }
                }
        }
}

void Print()
{
    fout<<cp<<'\n';
    for(int i=1; i<=n; i++)
        {
            if(L[i])
                fout<<i<<" "<<L[i]<<'\n';
        }
}

int main()
{
    Read();
    Cuplaj();
    Print();
}