#include <fstream>
#include <vector>
#include <string.h>

#define Ndim 10003
#define pb push_back
using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
int N,M,E,L[Ndim],R[Ndim];
bool VIZ[Ndim];
vector <int> G[Ndim];
void read()
{
    fin>>N>>M>>E;
    int a,b,i;
    for(i=1;i<=E;i++)
    {
        fin>>a>>b;
        G[a].pb(b);
    }

}
bool pairup(int nod)
{
    if(VIZ[nod])
        return 0;
    VIZ[nod] = 1;
    for(vector<int> :: iterator it = G[nod].begin();it!=G[nod].end();++it)
    {
        if(!R[*it])
        {
            L[nod] = *it;
            R[*it] = nod;
            return 1;
        }
    }
    for(vector<int> :: iterator it = G[nod].begin();it!=G[nod].end();++it)
    {
        if(pairup(R[*it]))
        {
            L[nod] = *it;
            R[*it] = nod;
            return 1;
        }
    }
    return 0;

}
void solve()
{
    int i,change;
    for(change = 1;change;)
    {
        change = 0;
        memset(VIZ,0,sizeof VIZ);
        for(i=1;i<=N;i++)
            if(!L[i])
                change|=pairup(i);
    }
}
void print()
{
    int sol = 0,i;
    for(i=1;i<=N;i++)
        sol += (L[i]>0);
    fout<<sol<<'\n';
    for(i=1;i<=N;i++)
        if(L[i] > 0)
            fout<<i<<' '<<L[i]<<'\n';
}
int main()
{
    read();
    solve();
    print();
    return 0;
}