#include <cstdio>
#include <vector>
#include <bitset>
#include <algorithm>

#define Nmax 10005

using namespace std;
int S,D,M,L[Nmax],R[Nmax],card;
bitset<Nmax>used;
vector<int> G[Nmax];

void Read()
{
    scanf("%d%d%d",&S,&D,&M);
    int a,b;
    for(int i = 1; i <= M; ++i)
    {
        scanf("%d%d",&a,&b);
        G[a].push_back(b);
    }
}

int cuplaj(int k)
{
    if(used[k]) return 0;
    used[k] = 1;
    for(vector<int>::iterator it = G[k].begin(); it != G[k].end(); ++it)
        if(!R[*it]) /// nu e cuplat cu nimeni *it
        {
            ///R[L[k]] = 0; /// optional, marcam decuplarea fostului L[k] - care e in dreapta
            R[*it] = k;
            L[k] = *it;
            return 1;
        }
    for(vector<int>::iterator it = G[k].begin(); it != G[k].end(); ++it)
        if(cuplaj(R[*it])) /// daca putem sa recuplam nodul cuplat cu *it
        {
           /// R[L[k]] = 0; /// optional, demarcam nodul din stanga corespondent nodul L[k] - din dreapta
            R[*it] = k;
            L[k] = *it;
            return 1;
        }
    return 0;
}


int main()
{
    freopen("cuplaj.in","r",stdin);
    freopen("cuplaj.out","w",stdout);

    Read();
    int ok = 1;
    while(ok)
    {
        ok = 0;
        for(int i = 1; i <= S; ++i)
            if(!L[i] && cuplaj(i))
            {
                ++card;
                ok = 1;
            }
        used = 0;
    }
    printf("%d\n",card);
    for(int i = 1; i <= S; ++i)
        if(L[i])
            printf("%d %d\n",i,L[i]);
    return 0;
}