#include <fstream>
#include <vector>
using namespace std;
ifstream cin ("cuplaj.in");
ofstream cout ("cuplaj.out");

int n,m,e,x,y,f[10010],t[10010],r,ok,tt[10010];
vector<int>v[10010];

int cp (int x)
{
    if (f[x]) return 0;
    f[x]=1;
    for (auto i:v[x])
    if (t[i]==-1 || cp(t[i]))
    {
        t[i]=x;
        tt[x]=i;
        ok=1;
        return 1;
    }
    return 0;
}

int main()
{
    cin>>n>>m>>e;
    for (int i=1; i<=e; i++)
    {
        cin>>x>>y;
        v[x].push_back(y);
    }
    for (int i=1; i<=m; i++)
    t[i]=-1;

    ok=1;
    while (ok)
    {
        ok=0;
        for (int j=1; j<=n; j++)
        f[j]=0;

        for (int i=1; i<=n; i++)
        if (!tt[i]) cp(i);

    }

    for (int i=1; i<=m; i++)
    if (t[i]>0) r++;
    cout<<r<<'\n';
    for (int i=1; i<=m; i++)
    if (t[i]>0) cout<<t[i]<<" "<<i<<'\n';


    return 0;
}