#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <vector>
using namespace std;

const int NMAX = 10010;

int N, M, E, A, B, L[NMAX], R[NMAX];
vector<int> G[NMAX];
bool Used[NMAX];

bool PairUp(int Node)
{
    if(Used[Node]) return 0;
    Used[Node] = 1;

    for(int i = 0; i < G[Node].size(); ++ i)
    {
        int Vec = G[Node][i];
        if(!R[Vec])
        {
            L[Node] = Vec;
            R[Vec] = Node;
            return 1;
        }
    }

    for(int i = 0; i < G[Node].size(); ++ i)
    {
        int Vec = G[Node][i];
        if(PairUp(R[Vec]))
        {
            L[Node] = Vec;
            R[Vec] = Node;
            return 1;
        }
    }

    return 0;
}

void MaxMatching()
{
    bool OK = 1;
    while(OK)
    {
        OK = 0;
        for(int i = 1; i <= N; ++ i) Used[i] = 0;
        for(int i = 1; i <= N; ++ i) if(!L[i] && PairUp(i)) OK = 1;
    }

    int Cnt = 0;
    for(int i = 1; i <= N; ++ i) if(L[i]) Cnt ++;

    printf("%i\n", Cnt);
    for(int i = 1; i <= N; ++ i) if(L[i]) printf("%i %i\n", i, L[i]);
}

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

    scanf("%i %i %i", &N, &M, &E);
    for(int i = 1; i <= E; ++ i)
    {
        scanf("%i %i", &A, &B);
        G[A].push_back(B);
    }

    MaxMatching();
}