#define NMAX 10005
#include <fstream>
#include <vector>
#include <bitset>
using namespace std;

ifstream f("cuplaj.in");
ofstream g("cuplaj.out");

int n, m, p;
vector<int> graph[NMAX];
int vs[NMAX], vd[NMAX];
bitset<NMAX> viz;
vector<pair<int, int> >rez;

void read()
{
    int u, v;

    f>>n>>m>>p;
    for(int i = 1; i <= p; ++i)
    {
        f>>u>>v;
        graph[u].push_back(v);
    }
}

bool findv(int vf)
{
    if(viz[vf])
        return false;
    viz[vf] = 1;
    for(auto &v:graph[vf])
        if(vs[v] == 0)
        {
            vs[v] = vf;
            vd[vf] = v;
            return true;
        }
    for(auto &v:graph[vf])
        if(findv(vs[v]))
        {
            vs[v] = vf;
            vd[vf] = v;
            return true;
        }
    return false;
}





void solve()
{
    bool ok = true;
    while(ok)
    {
        ok = false;
        viz.reset();
        for(int i = 1; i <= n; ++i)
            if(vd[i] == 0)
                ok = (ok | findv(i));
    }
}

void write()
{
    for(int i = 1; i <= n; ++i)
        if(vd[i] != 0)
            rez.push_back({i, vd[i]});
    g<<rez.size()<<'\n';
    for(auto &i:rez)
        g<<i.first<<" "<<i.second<<'\n';
}


int main()
{
    read();
    solve();
    write();
    return 0;
}