#include <iostream>
#include <fstream>
#include <string.h>
#include <vector>

using namespace std;

int N, M, E;
int l [10001], r[10001];
bool vizitat [10001];
//bool term = false;
vector <int> G[10001];


int link (int x)
{
    //cout<<"LINKUI NODUL "<<x<<"\n";
    //if (term)
        //std::terminate();
    //if(x==3)
       // term = true;
    //if(x==3)
    //std::terminate();
    if(vizitat[x])
        return 0;
    vizitat[x] = 1;
    //for(auto i = G[x].begin(); i < G[x].end(); ++i)
    //    cout<<r[*i]<<" ";
    //cout<<"\n";
    for(auto i = G[x].begin(); i < G[x].end(); ++i)
        if(!r[*i])
            {
                //cout<<"caut nod liber in stanga... \n";
                l[x] = *i;
                r[*i] = x;
                return 1;

            }
    for(auto i = G[x].begin(); i < G[x].end(); ++i)  ///dc nu am gasit nod liber in dreapta incercam sa reconectam unul
        if(link (r[*i]))
            {
                l[x] = *i;
                r[*i] = x;
                return 1;
            }
    return false;

}

int main()
{
    ifstream in ("cuplaj.in");
    ofstream out ("cuplaj.out");

    int x, y, sol = 0;

    in >> N >> M >> E;
    for(int i = 0; i < E; ++i)
        {
            in >> x >> y;
            G[x].push_back(y);  //liste de adiacenta pt ca da
        }
    bool ok = false;
    //cout<<"INCEP REZOLVAREA!\n";
    while(!ok)
    {
        ok = true;
        memset(vizitat, 0, 10001);
        for (int i = 1; i <= N; ++i)
            if(!l[i])
                if(link(i))
                    ok = false;
    }
    //cout<<"AFISAREA:\n";
    for(int i = 1; i <= N; ++i)
        if (l[i])
            ++sol;
    out<<sol<<"\n";
    for(int i = 1; i <= N; ++i)
        if(l[i])
            out<<i<<" "<<l[i]<<"\n";
    return 0;
}