#include <bits/stdc++.h>
using namespace std;
long long n, k;
const long long maxN = 2 * (long long)1e5 + 100;
long long x[maxN], y[maxN];
bool ok[maxN];
bool ok2[maxN];
set<pair<long long, long long> > s;
void check(long long a, long long b) {
  memset(ok, 0, sizeof ok);
  long long r = n;
  for (long long i = 1; i <= n; i++) {
    if (make_pair(x[i] + x[r], y[i] + y[r]) < make_pair(a, b)) continue;
    if (i > r) break;
    while (r >= 1 && make_pair(x[i] + x[r], y[i] + y[r]) >= make_pair(a, b))
      r--;
    r++;
    if (y[i] + y[r] == b && x[i] + x[r] == a && r <= n) {
      ok[i] = true;
      ok[r] = true;
    }
  }
  long long sum = 0;
  for (long long i = 1; i <= n; i++) {
    if (ok[i]) sum++;
  }
  if (sum >= n - k) {
    s.insert(make_pair(a, b));
  }
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  srand(228);
  cin >> n >> k;
  vector<pair<long long, long long> > all(n);
  for (auto& t : all) cin >> t.first >> t.second;
  sort(all.begin(), all.end());
  for (long long i = 1; i <= n; i++) {
    x[i] = all[i - 1].first;
    y[i] = all[i - 1].second;
  }
  if (k >= n) {
    cout << -1;
    return 0;
  }
  for (long long i = 1; i <= min(n, k + 3); i++) {
    for (long long j = max(i, n - k - 2); j <= n; j++) {
      check(x[i] + x[j], y[i] + y[j]);
    }
  }
  cout << s.size() << '\n';
  for (auto it : s) {
    cout << fixed << setprecision(10) << 1.0 * it.first / 2 << " "
         << 1.0 * it.second / 2 << '\n';
  }
  return 0;
}
