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

using namespace std;

const char iname[] = "cuplaj.in";
const char oname[] = "cuplaj.out";

#define MAXN  20005
#define FOR(i, a, b)  for (int i = (int)(a); i <= (int)(b); ++ i)

struct list {
    int node, cap, flow;
    list *nxt, *dup;
} ;

typedef list* plist;

plist adj[MAXN], edge[MAXN];    int n, m, q[MAXN], sel[MAXN], src, sink;


void alloc_edge(plist &nou, plist &dup, int i, int j)
{
    nou = new list, dup = new list;
    nou->node = j, dup->node = i;
    nou->dup = dup, dup->dup = nou;
    nou->nxt = adj[i], dup->nxt = adj[j];
    adj[i] = nou, adj[j] = dup;
}

void read_in(void)
{
    FILE *fi = fopen(iname, "r");
    int cnt_edges, x, y;
    plist nou, dup;

    fscanf(fi, "%d %d %d", &n, &m, &cnt_edges);
    for (; cnt_edges --; )
    {
        fscanf(fi, "%d %d", &x, &y);
        alloc_edge(nou, dup, x, y + n);
        nou->cap = 1, nou->flow = dup->cap = dup->flow = 0;
    }
    fclose(fi);

    src = 0;
    FOR (i, 1, n) {
        alloc_edge(nou, dup, src, i);
        nou->cap = 1, nou->flow = dup->cap = dup->flow = 0;
    }
    sink = n+m+1;
    FOR (i, n + 1, n + m) {
        alloc_edge(nou, dup, i, sink);
        nou->cap = 1, nou->flow = dup->cap = dup->flow = 0;
    }
}

int BFS(const int src, const int sink)
{
    int h, t;
    plist it;

    memset(sel, 0, sizeof(sel));

    edge[src] = 0;
    for (sel[q[h = t = 0] = src] = 1; h <= t; ++ h)
    {
        for (it = adj[q[h]]; it; it = it->nxt)
            if ((it->cap - it->flow) > 0 && !sel[it->node])
            {
                sel[q[++ t] = it->node] = 1;
                edge[it->node] = it;
                if (it->node == sink)
                {
                    for (it = edge[sink]; it; it = edge[it->dup->node])
                        it->flow ++, it->dup->flow --;
                    return 1;
                }
            }
    }
    return 0;
}

int main(void)
{
    read_in();
    int cuplaj = 0;
    while (BFS(src, sink))  cuplaj ++;

    FILE *fo = fopen(oname, "w");
    fprintf(fo, "%d\n", cuplaj);
    FOR (i, 1, n)
    {
        for (plist it = adj[i]; it; it = it->nxt)
            if (it->flow == 1)
                fprintf(fo, "%d %d\n", i, it->node - n);
    }
    fclose(fo);

    return 0;
}