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

#define Nmax 10010
#define PB push_back
#define IT vector<int> :: iterator

int N, M, L[Nmax], R[Nmax], Used[Nmax], X, Y, E;
vector<int> G[Nmax];

int PairUp(int Node)
{
    if(Used[Node]) return 0;
    Used[Node] = 1;
    for(IT it = G[Node].begin(); it != G[Node].end(); ++it)
        if(!R[*it] || PairUp(R[*it]))
        {
            L[Node] = *it;
            R[*it] = Node;
            return 1;
        }
    return 0;
}

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

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", &X, &Y), G[X].PB(Y);
    printf("%i\n", MaxMatching());
    for(int i = 1; i <= N; i++)
        if(L[i])
            printf("%i %i\n", i, L[i]);
    return 0;
}