УРКОП 2011: K

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <vector>

#define N 1005
#define pb push_back
#define INF int(1e9)

#define mp make_pair
#define x  first
#define y second

using namespace std;

pair<int, int> vect[N];
vector< pair<int, int> > ans;

int main() {
    int n, k;
    cin >> n >> k;

    for (int i = 0; i < n; i++) {
        int x, y;
        cin >> x >> y;
        vect[i] = mp(x, y);
    }

    sort(vect, vect + n);

    int t = 1;
    while (vect[t].x == vect[t - 1].x && t < n) t++;

    if (k == 1) {
        ans.pb( mp(vect[0].x,     vect[0].y) );
        ans.pb( mp(vect[0].x,     vect[0].y - 1) );
        ans.pb( mp(vect[0].x - 1, vect[0].y - 1) );
        ans.pb( mp(vect[0].x - 1, vect[0].y) );
    }

    if (k == 2) {
        ans.pb(vect[1]);
        ans.pb(vect[0]);
        ans.pb(mp(-INF, INF));
    }

    if (k > 2) {

        if (t >= k) {
            ans.pb(vect[k - 1]);
            ans.pb(vect[0]);
            ans.pb(mp(-INF, INF));
        }
        else {
            ans.pb( mp(vect[k - 1].x,-INF) );
            ans.pb( mp(-INF,-INF) );
            ans.pb( mp(-INF, INF) );
            ans.pb( mp(vect[k - 1].x - 1, INF) );
            ans.pb( vect[k - 1] );
        }
    }

    cout << ans.size() << endl;
    for (int i = ans.size() - 1; i >= 0; i--)
        cout << ans[i].first << " " << ans[i].second << endl;

    return 0;
}