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

const int N = 10005;
vector <int> vec[N];
bool ok, cup[N], viz[N];
int n, m, k, cuplaj[N], a, b, sol;

int cupleaza(int nod)
{
    int i;
    if(viz[nod])
        return 0;
    viz[nod] = 1;
    for(i = 0; i < vec[nod].size(); ++i) {
        if(!cuplaj[vec[nod][i]]) {
            cuplaj[vec[nod][i]] = nod;
            cup[nod] = 1;
            return 1;
        }
    }
    for(i = 0; i < vec[nod].size(); ++i) {
        if(cuplaj[vec[nod][i]] != nod && cupleaza(cuplaj[vec[nod][i]])) {
            cuplaj[vec[nod][i]] = nod;
            cup[nod] = 1;
            return 1;
        }
    }
    return 0;
}

int main()
{
    int i;
    freopen ("cuplaj.in", "r", stdin);
    freopen ("cuplaj.out", "w", stdout);
    scanf("%d %d %d", &n, &m, &k);
    for(i = 1; i <= k; ++i) {
        scanf("%d %d", &a, &b);
        vec[a].push_back(b);
    }
    ok = 1;
    while(ok) {
        memset(viz, 0, sizeof(viz));
        ok = 0;
        for(i = 1; i <= n; ++i) {
            if(!cup[i] && cupleaza(i)) {
                ++sol;
                ok = 1;
            }
        }
    }
    printf("%d\n", sol);
    for(i = 1; i <= m; ++i)
        if(cuplaj[i])
            printf("%d %d\n", cuplaj[i], i);
    return 0;
}