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

FILE *fin = freopen("cuplaj.in", "r", stdin);
FILE *fout = freopen("cuplaj.out", "w", stdout);

const int MAX_N = 10005;
int N, M, E;
int cuplaj;
int left[MAX_N], right[MAX_N];
bool used[MAX_N];
vector < int > G[MAX_N];

int PairUp(int X)
{
    if (used[X])
        return 0;
    used[X] = 1;
    vector < int > :: iterator it;
    for (it = G[X].begin(); it != G[X].end(); it++)
        if (!right[*it])
        {
            left[X] = *it;
            right[*it] = X;
            return 1;
        }

    for (it = G[X].begin(); it != G[X].end(); it++)
        if (PairUp(right[*it]))
        {
            left[X] = *it;
            right[*it] = X;
            return 1;
        }

    return 0;
}

int main()
    {
        scanf("%d%d%d", &N, &M, &E);

        for (int i = 1, u, v; i <= E; i++)
        {
            scanf("%d%d", &u, &v);
            G[u].push_back(v);
        }

        int sol = 1;

        while (sol)
        {
            sol = 0;
            memset(used, 0, sizeof(used));
            for (int i = 1; i <= N; i++)
                if (!left[i])
                    sol |= PairUp(i);
        }
        for (int i = 1; i <= N; i++)
            cuplaj += (left[i] > 0);

        printf("%d\n", cuplaj);

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