///O(sqrt(n + m) * k)
#include <bits/stdc++.h>

using namespace std;

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

int n, m, k, ans;
int st[10005], dr[10005];
bool viz[10005];
vector <int> L[10005];

inline void Read()
{
    int i, x, y;
    fin >> n >> m >> k;
    for(i = 1; i <= k; i++)
    {
        fin >> x >> y;
        L[x].push_back(y);
    }
}

inline bool Cuplaj(int nod)
{
    int i, nnod;
    if(viz[nod]) return false;
    viz[nod] = true;

    for(i = 0; i < L[nod].size(); i++)
    {
        nnod = L[nod][i];
        if(!dr[nnod])
        {
            st[nod] = nnod;
            dr[nnod] = nod;
            return true;
        }
    }
    for(i = 0; i < L[nod].size(); i++)
    {
        nnod = L[nod][i];
        if(Cuplaj(dr[nnod]))
        {
            st[nod] = nnod;
            dr[nnod] = nod;
            return true;
        }
    }
    return false;
}

void Solve()
{
    bool gata;
    int i;
    gata = 0;
    while(!gata)
    {
        gata = 1;
        for(i = 1; i <= n; i++)
            viz[i] = 0;
        for(i = 1; i <= n; i++)
            if(!st[i] && Cuplaj(i))
            {
                ans++;
                gata = 0;
            }
    }
    fout << ans << "\n";
    for(i = 1; i <= n; i++)
        if(st[i])
            fout << i << " " << st[i] << "\n";
}

int main()
{
    Read();
    Solve();
    return 0;
}