#include <fstream>
#include <vector>
#include <cstring>
using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
#define dim 10005
vector <int> v[dim];
int n, m, e,viz[dim],a[dim],b[dim];
void read()
{
    int x, y;
    fin>>n >>m >>e;
    for(int i=1;i<=e;++i)
    {
        fin>>x >>y;
        v[x].push_back(y);
    }
}
int pairup(int nod)
{
    if(viz[nod]==1)
        return 0;
    viz[nod]=1;
    for(int k=0;k<(int)v[nod].size();++k)
        if(!b[v[nod][k]])
        {
            a[nod]=v[nod][k];
            b[v[nod][k]]=nod;
            return 1;
        }
        else
        if(pairup(b[v[nod][k]]))
            {
            a[nod]=v[nod][k];
            b[v[nod][k]]=nod;
            return 1;
        }


    return 0;
}
void solve()
{
    int i,ok,cuplaj=0;

    do
    {
        ok=0;
        memset(viz,0,sizeof(viz));
        for(i=1;i<=n;++i)
            if(!a[i] && pairup(i))
            {
                ok=1;
                ++cuplaj;
            }

    }while(ok);
    fout<<cuplaj <<'\n';
}
void print()
{
    for(int i=1;i<=n;++i)
        if(a[i]!=0)
            fout<<i <<" " <<a[i] <<'\n';
}
int main()
{
    read();
    solve();
    print();
    return 0;
}