#include <fstream>
#include <vector>
using namespace std;
ifstream f("cuplaj.in");
ofstream g("cuplaj.out");

int N, M, dr[10005], st[10005], Q, cuplate, x, y, viz[10005], ok=1;
vector < int > G[10005];

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

int main()
{
    f>>N>>M>>Q;
    while (Q--)
        f>>x>>y, G[x].push_back(y);

    while (ok)
    {
        for (int i=1; i<=N; ++i)
            viz[i]=0; ok=0;
        for (int i=1; i<=N; ++i)
            if (!st[i] && cuplaj(i))
                ++cuplate, ok=1;
    }

    g<<cuplate<<'\n';
    for (int i=1; i<=N; ++i)
        if (st[i])
            g<<i<<' '<<st[i]<<'\n';
    return 0;
}