#include <fstream>
#include <vector>

using namespace std;

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

vector<int> v[10001];
vector<bool> used;
int n,m,E,x,y,l[10001],r[10001],sol;

bool now_kiss(int nod)
{
    if(used[nod])
        return false;
    used[nod] = true;
    for(unsigned int i=0;i<v[nod].size();i++)
        if(r[v[nod][i]] == 0 || now_kiss(v[nod][i]) )
        {
            r[v[nod][i]] = nod;
            l[nod] = v[nod][i];
            return true;
        }
    return false;
}

int main()
{
    fin>>n>>m>>E;
    for(int i=1;i<=E;i++)
    {
        fin>>x>>y;
        v[x].push_back(y);
    }
    bool ch;
    while(ch)
    {
        ch = false;
        used.assign(n+1,0);
        for(int i=1;i<=n;i++)
            if(l[i] == 0)
                if(now_kiss(i))
                {
                    sol++;
                    ch = true;
                }
    }
    fout<<sol<<'\n';
    for(int i=1;i<=n;i++)
        if(l[i])
            fout<<i<<' '<<l[i]<<'\n';
    fin.close();
    fout.close();
    return 0;
}