#include <iostream>
#include <vector>
#include <set>
#include <queue>
#include <algorithm>
#include <string>
#include <fstream>
#include <cctype>
#include <iomanip>
#include <cmath>
#include <cstring>
#include <map>
#include <bitset>
#include <stack>

using namespace std;

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

vector<int> V[10001];
int L[10001];
int R[10001];
bitset<10001> used;

bool cuplaj(int node)
{
    if(used[node])
        return false;
    used[node] = true;
    for(vector<int>::iterator it = V[node].begin(); it != V[node].end(); it++)
        if(!R[*it] || cuplaj(R[*it]))
        {
            L[node] = *it;
            R[*it] = node;
            return true;
        }
    return false;
}

int main()
{
    //freopen("1.in");
    //freopen("1.out");
    int n,m,e,x,y;
    fin>>n>>m>>e;
    for(int i = 1; i <= e; i++)
    {
        fin>>x>>y;
        V[x].push_back(y);
    }
    bool ok = true;
    int res = 0;
    while(ok)
    {
        ok = false;
        used.reset();
        for(int i = 1; i <= n; i++)
            if(!L[i] && cuplaj(i))
            {
                ok = true;
                res++;
            }
    }
    fout<<res<<'\n';
    for(int i = 1; i <= n; i++)
        if(L[i])
            fout<<i<<' '<<L[i]<<'\n';

    return 0;
}


//FILE!!!