#include <cstdio>
#include <cstring>
#include <vector>
#define pb push_back
#define NODES 10002
using namespace std;

int dr[NODES], st[NODES], n, m, e, i, MAX, a, b;
bool visited[NODES], sw;
vector <int> adj[NODES];

bool couple(int node)
{
    if(visited[node])
        return 0;
    visited[node]=1;
    for(vector <int> :: iterator it=adj[node].begin(); it!=adj[node].end(); ++it)
        if(!st[*it] || couple(st[*it]) )
        {
            st[*it]=node;
            dr[node]=*it;
            return 1;
        }
    return 0;
}

int main()
{
    freopen("cuplaj.in", "r", stdin);
    freopen("cuplaj.out", "w", stdout);
    scanf("%d %d %d", &n, &m, &e);
    while(e--)
    {
        scanf("%d %d", &a, &b);
        adj[a].pb(b);
    }
    while(!sw)
    {
        sw=1;
        memset(visited, 0, sizeof(visited));
        for(i=1;i<=n;++i)
            if(!dr[i] && couple(i))
                ++MAX, sw=0;
    }
    printf("%d\n", MAX);
    for(i=1;i<=n;++i)
        if(dr[i])
            printf("%d %d\n", i, dr[i]);
    return 0;
}