#include <bits/stdc++.h>
using namespace std;
const int MAXN = 200000;
const int INF = 0x3f3f3f3f;
template <class T>
void Read(T &x) {
  x = 0;
  char c = getchar();
  bool flag = 0;
  while (c < '0' || '9' < c) {
    if (c == '-') flag = 1;
    c = getchar();
  }
  while ('0' <= c && c <= '9') {
    x = x * 10 + c - '0';
    c = getchar();
  }
  if (flag) x = -x;
}
const double eps = 1e-8;
inline int Sign(const double x) {
  if (x > eps)
    return 1;
  else if (x < -eps)
    return -1;
  else
    return 0;
}
struct Point {
  double x, y;
  Point() {}
  Point(double a, double b) : x(a), y(b) {}
  bool operator<(const Point &a) const {
    if (Sign(x - a.x) == 0)
      return Sign(y - a.y) < 0;
    else
      return Sign(x - a.x) < 0;
  }
  bool operator==(const Point &a) const {
    return Sign(x - a.x) == 0 && Sign(y - a.y) == 0;
  }
  bool operator!=(const Point &a) const { return !((*this) == a); }
  Point operator+(const Point &a) const { return Point(x + a.x, y + a.y); }
  Point operator-(const Point &a) const { return Point(x - a.x, y - a.y); }
  Point operator/(const double v) const { return Point(x / v, y / v); }
} A[MAXN + 10];
int n, k;
vector<Point> ans;
map<Point, bool> mp;
int main() {
  Read(n), Read(k);
  for (int i = 1; i <= n; ++i) scanf("%lf%lf", &A[i].x, &A[i].y);
  sort(A + 1, A + n + 1);
  if (n <= k) {
    puts("-1");
    return 0;
  }
  ans.clear();
  mp.clear();
  for (int i = 1; i <= n && i - 1 <= k; ++i) {
    for (int j = n; j >= i && i - 1 + n - j <= k; --j) {
      Point ct = (A[i] + A[j]) / 2.0;
      int cnt = 0;
      int l = i + 1, r = j - 1;
      while (l <= r) {
        if ((A[l] + A[r]) / 2.0 == ct)
          ++l, --r;
        else if (ct + ct - A[l] < A[r])
          ++cnt, --r;
        else
          ++cnt, ++l;
      }
      if (cnt + i - 1 + n - j <= k && !mp[ct]) ans.push_back(ct), mp[ct] = true;
    }
  }
  printf("%d\n", ans.size());
  for (int i = 0; i < ans.size(); ++i)
    printf("%.6f %.6f\n", ans[i].x, ans[i].y);
}
