#include <bits/stdc++.h>
using namespace std;
int n, m;
bool debug = false;
int k;
int dx[4] = {0, 1, 0, -1}, dy[4] = {1, 0, -1, 0};
vector<pair<long long, long long>> v;
set<pair<long long, long long>> ans;
long long cx, cy;
int c;
bool ck(int i, int j) {
  pair<long long, long long> pp = {cx, cy};
  for (; i <= j;) {
    pair<long long, long long> t = {v[i].first + v[j].first,
                                    v[i].second + v[j].second};
    if (pp == t) {
      i++;
      j--;
      continue;
    }
    c++;
    if (c > k) return 0;
    if (t > pp)
      j--;
    else
      i++;
  }
  return 1;
}
int main() {
  scanf("%d%d", &n, &k);
  if (n <= k) {
    puts("-1");
    return 0;
  }
  for (int i = 0, x, y; i < n; i++) {
    scanf("%d%d", &x, &y);
    v.push_back({x, y});
  }
  sort(v.begin(), v.end());
  for (int i = 0; i < k + 1; i++) {
    for (int j = n - 1; j > n - 1 - k - 1; j--)
      if (i <= j) {
        cx = v[i].first + v[j].first;
        cy = v[i].second + v[j].second;
        c = 0;
        if (c <= k && ck(0, n - 1)) {
          ans.insert({cx, cy});
        }
      }
  }
  printf("%d\n", ans.size());
  for (auto x : ans) printf("%lf %lf\n", x.first * 0.5, x.second * 0.5);
  return 0;
}
