#include <bits/stdc++.h>
#define pb push_back
#define maxN 20002
#define pii pair < int, int >
#define mp make_pair
#define f first
#define s second
using namespace std;
int n, m, e, l, Pair[maxN], d;
vector < int > V[maxN];
pii ans[maxN];
bool Left[maxN], vis[maxN];
int Pairup(int x)
{
    int y, i = 0;
    if (vis[x])
        return 0;
    vis[x] = 1;
    for (i = 0; i < V[x].size(); ++ i)
        if (Pair[y = V[x][i]] == -1 || Pairup(Pair[y]))
        {
            Pair[x] = y;
            Pair[y] = x;
            d = y;
            return 1;
        }
    return 0;
}
void read()
{
    freopen("cuplaj.in", "r", stdin);
    scanf("%d %d %d", &n, &m, &e);
    for (int i = 1; i <= e; ++ i)
    {
        int x, y;
        scanf("%d %d", &x, &y);
        //Left[x] = 1;
        y += n;
        V[x].pb(y);
        V[y].pb(x);
    }
}
void solve()
{
    int i, ok = 0;
    memset(Pair, -1, sizeof(Pair));
    do
    {
        ok = 0;
        memset(vis, 0, sizeof(vis));
        for (i = 1; i <= n; ++ i)
            if (Pair[i] == -1)
                ok |= Pairup(i);
    }
    while (ok);

    for (i = 1; i <= n; ++ i)
        if (Pair[i] != -1)
            ans[++ l] = mp(i, Pair[i]);
}
void write()
{
    freopen("cuplaj.out", "w", stdout);
    printf("%d\n", l);
    for (int i = 1; i <= l; ++ i)
        printf("%d %d\n", ans[i].f, ans[i].s - n);
}
int main()
{
    read();
    solve();
    write();
    return 0;
}