#include <bits/stdc++.h>

using namespace std;
ifstream f("cuplaj.in");
ofstream g("cuplaj.out");
int nani[10005],l[10005],r[10005],n,cmax;
vector <int> v[10005];
int cupleaza (int nod)
{
    int i,it;
    nani[nod]=1;
    for (i=0;i<v[nod].size();i++)
    {
        it=v[nod][i];
        if (r[it]==0)
        {
            l[nod]=it;
            r[it]=nod;
            return 1;
        }
    }
    for (i=0;i<v[nod].size();i++)
    {
        it=v[nod][i];
        if (!nani[r[it]]&&cupleaza(r[it])!=0)
        {
            l[nod]=it;
            r[it]=nod;
        }
    }
    return 0;
}
void solve ()
{
    int ok=1,i;
    while (ok==1)
    {
        ok=0;
        for (i=1;i<=n;i++)
        {
            nani[i]=0;
        }
        for (i=1;i<=n;i++)
        {
            if (l[i]==0&&nani[i]==0)
            {
                if (cupleaza(i)!=0)
                {
                    ok=1;
                    cmax++;
                }
            }
        }
    }
}int m,e,x,y,i;
int main()
{
    f>>n>>m>>e;
    cmax=0;
    for (i=1;i<=e;i++)
    {
        f>>x>>y;
        v[x].push_back(y);
    }
    solve();
    g<<cmax<<'\n';
    for (i=1;i<=n;i++)
    {
        if (l[i]!=0)
        {
            g<<i<<" "<<l[i]<<'\n';
        }
    }
    return 0;
}