#include <cstdio>
#include <vector>
 
using namespace std;
 
#define MAX_N 10005
#define foreach(V) for (vector <int>::iterator it = (V).begin(); it != (V).end(); ++it)
 
int N, M, NR;
vector <int> G[MAX_N];
bool viz[MAX_N];
int C[MAX_N], R[MAX_N];
 
void citire()
{
    scanf("%d %d %d",&N, &M, &NR);
 
    for(;NR;NR--)
    {
        int x, y;
        scanf("%d %d",&x, &y);
        G[x].push_back(y);
    }
}
 
bool pairup(int nod)
{
    if(viz[nod]) return false;
    viz[nod] = true;
 
    foreach(G[nod])
        if(!R[*it])
        {
            C[nod] = *it;
            R[*it] = nod;
            return 1;
        }
    foreach(G[nod])
        if(pairup(R[*it]))
        {
            C[nod] = *it;
            R[*it] = nod;
            return 1;
        }
    return 0;
}
 
void solve()
{
    for(bool ok = 1; ok;)
    {
        ok = 0;
        memset (viz, 0, sizeof viz);
        for(int i = 1; i <= N; ++i)
            if(C[i] == 0)
                ok |= pairup(i);
    }
    int Rez = 0;
    for(int i = 1; i <= N; ++i)
        if(C[i])
            ++Rez;
    printf("%d\n",Rez);
 
    for(int i = 1; i <= N; ++i)
        if(C[i])
            printf("%d %d\n",i, C[i]);
}
 
int main()
{
    freopen("cuplaj.in","rt",stdin);
    freopen("cuplaj.out","wt",stdout);
 
    citire();
    solve();
}