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

typedef vector <int> :: iterator iter;
vector <int> G[MAX];

int viz[MAX], dr[MAX], st[MAX];

bool cuplaj(int nod)
{
    if(viz[nod])
       return 0;
    viz[nod] = 1;

    for(iter it = G[nod].begin() ; it != G[nod].end() ; it++)
    {
        if(!st[*it])
        {
            st[*it] = nod;
            dr[nod] = *it;
            return 1;
        }
    }
    for(iter it = G[nod].begin() ; it != G[nod].end() ; it++)
    {
        if(cuplaj(st[*it]))
        {
            st[*it] = nod;
            dr[nod] = *it;
            return 1;
        }
    }
    return 0;
}

int main()
{
    int cpl, n, m, e, x, y, ok, i;
    fin >> n >> m >> e;
    while(e--)
    {
        fin >> x >> y;
        G[x].push_back(y);
    }
    do{
        ok = 0;
        memset(viz, 0, sizeof(viz));
        for(i = 1 ; i <= n ; i++)
        {
            if(!dr[i])
                ok |= cuplaj(i);
        }
    }while(ok);
    cpl = 0;
    for(i = 1 ; i <= n ; i++)
        cpl += (dr[i] != 0);
    cout << cpl << "\n";
    for(i = 1 ; i <= n ; i++)
    {
        if(dr[i])
            cout << i << " " << dr[i] << "\n";
    }
}