#include <bits/stdc++.h>
using namespace std;
ifstream f("cuplaj.in");
ofstream g("cuplaj.out");
int n, m, e, sol, st[10005], dr[10005];
bool tried[10005];
vector <int> v[10005];
bool cupleaza(int k)
{
    if(tried[k] == 1)
        return 0;
    tried[k] = 1;
    for(int i = 0; i < v[k].size(); i ++)
        if(dr[v[k][i]] == 0)
        {
            dr[v[k][i]] = k;
            st[k] = v[k][i];
            sol ++;
            return 1;
        }
    for(int i = 0; i < v[k].size(); i ++)
        if(cupleaza(dr[v[k][i]]))
        {
            dr[v[k][i]] = k;
            st[k] = v[k][i];
            return 1;
        }
    return 0;
}
void cuplaj()
{
    bool ok = true;
    while(ok)
    {
        ok = false;
        for(int i = 1; i <= n; i ++)
            tried[i] = 0;
        for(int i = 1; i <= n; i ++)
            if(st[i] == 0)
                ok = ok | cupleaza(i);
    }

}
int main()
{
    f >> n >> m >> e;
    for(int i = 1; i <= e; i ++)
    {
        int x, y;
        f >> x >> y;
        v[x].push_back(y);
    }
    cuplaj();
    g << sol << "\n";
    for(int i = 1; i <= n; i ++)
        if(st[i])
        g << i << " " << st[i] << "\n";
    return 0;
}