#include <bits/stdc++.h>
#define N 10005
#define pb push_back

using namespace std;
vector<int>v[N];
int l[N], r[N], sol, n, m, e, i, x, y, ok;
bitset<N>viz;
bool pairup(int nod)
{
    if(viz[nod])
        return 0;
    viz[nod] = 1;
    for(auto it : v[nod])
        if(!r[it] || pairup(r[it]))
        {
            l[nod] = it;
            r[it] = nod;
            return 1;
        }
    return 0;
}
int main()
{
    freopen("cuplaj.in", "r", stdin);
    freopen("cuplaj.out", "w", stdout);
    scanf("%d%d%d", &n, &m, &e);
    for(; e; e--)
    {
        scanf("%d%d", &x, &y);
        v[x].pb(y);
    }
    for(ok = 1; ok;)
    {
        ok = 0;
        viz = 0;
        for(i = 1; i <= n; i++)
            if(!l[i] && pairup(i))
            {
                ok = 1;
                sol++;
            }
    }
    printf("%d\n", sol);
    for(i = 1; i <= n; i++)
        if(l[i])
            printf("%d %d\n", i, l[i]);
    return 0;
}