#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;   
}