#include <iostream>
#include <fstream>
#include <vector>
#include <cstring>
using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
#define MAX 10010
#define cout fout
typedef vector<int>::iterator iter;
vector<int> G[MAX];
int viz[MAX], st[MAX], dr[MAX];


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

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

    int s = 0;
    for(i = 1 ; i <= n ; i++)
    {
        s += (dr[i]>0);
    }
    cout << s << "\n";
    for(i = 1 ; i <= n ; i++)
    {
        if(dr[i] > 0)
        {
            cout << i << " " << dr[i] << "\n";
        }
    }
}