#include <bits/stdc++.h>
using namespace std;
const double pi = acos(-1.0);
int n, k;
pair<int, int> p[200000 + 10], o, q;
set<pair<int, int> > ans;
int main() {
  int i, j, t, l, r;
  scanf("%d%d", &n, &k);
  for (i = 1; i <= n; ++i) scanf("%d%d", &p[i].first, &p[i].second);
  sort(p + 1, p + n + 1);
  if (k < n) {
    for (i = 0; i <= k; ++i)
      for (j = 0; i + j <= k; ++j) {
        o = make_pair(p[i + 1].first + p[n - j].first,
                      p[i + 1].second + p[n - j].second);
        t = i + j;
        l = i + 2, r = n - j - 1;
        while (l <= r) {
          q = make_pair(o.first - p[l].first, o.second - p[l].second);
          if (q < p[r])
            ++t, --r;
          else if (q > p[r])
            ++t, ++l;
          else
            ++l, --r;
        }
        if (t <= k) ans.insert(o);
      }
    printf("%d\n", ((int)ans.size()));
    for (set<pair<int, int> >::iterator itr = ans.begin(); itr != ans.end();
         ++itr)
      printf("%.1lf %.1lf\n", (*itr).first / 2.0, (*itr).second / 2.0);
  } else
    printf("-1\n");
  return 0;
}
