#include <bits/stdc++.h>

using namespace std;

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

int n, m, e, l[10005], r[10005];
bool k[10005];
bool p;
vector <int> v[10005];

bool Cuplaj(int nod)
{
    if(k[nod]) return 0;

    k[nod] = true;

    for(int i = 0; i < v[nod].size(); i++)
    {
        int child = v[nod][i];

        if(!r[child])
        {
            r[child] = nod;
            l[nod] = child;
            return 1;
        }
    }
    for(int i = 0; i < v[nod].size(); i++)
    {
        int child = v[nod][i];
        if(Cuplaj(r[child]))
        {
            r[child] = nod;
            l[nod] = child;
            return 1;
        }
    }
    return 0;
}
int main()
{
    fin >> n >> m >> e;

    while(e--)
    {
        int a, b;
        fin >> a >> b;
        v[a].push_back(b);
    }
    p = 1;

    while(p)
    {
        p = 0;
        memset(k, 0, sizeof(k));
        for(int i = 1; i <= n; i++)
            if(!l[i])
                p |= Cuplaj(i);

    }

    int ans = 0;
    for(int i = 1; i <= n; i++)
        if(l[i])
            ans++;
    fout << ans << '\n';
    for(int i = 1; i <= n; i++)
        if(l[i])
        fout << i << " " << l[i] << '\n';


    return 0;
}