#include <cstdio>
#include <vector>
#include <cstring>

using namespace std;

const int NMAX = 1000;

vector <int> g[NMAX+5];
bool vis[NMAX+5];

int right[NMAX+5], left[NMAX+5];

bool pairUp(int node)
{
    if(vis[node]) return false;
    vis[node] = true;
    for(int i=0; i<g[node].size(); i++)
    {
        int right_node = g[node][i];
        if(left[right_node] == 0 || pairUp(right_node))
        {
            left[right_node] = node;
            right[node] = right_node;
            return true;
        }
    }
}

int main()
{
    freopen("cuplaj.in", "r", stdin);
    freopen("cuplaj.out", "w", stdout);
    int n, m, e;
    scanf("%d%d%d", &n, &m, &e);
    for(int i=0; i<e; i++)
    {
        int x, y;
        scanf("%d%d", &x, &y);
        g[x].push_back(y);
    }
    bool ok = true;
    while(ok)
    {
        ok = false;
        memset(vis, 0, sizeof(vis));
        for(int i=1; i<=n; i++)
            if(right[i] == 0 && pairUp(i)) ok = true;
    }
    int ans = 0;
    for(int i=1; i<=n; i++)
        if(right[i]) ans++;
    printf("%d\n", ans);
    for(int i=1; i<=n; i++)
        if(right[i]) printf("%d %d\n", i, right[i]);
    return 0;
}