#include <bits/stdc++.h>
using namespace std;
struct point {
  int x, y;
} A[210000];
bool operator<(point i, point j) {
  if (i.x != j.x) return i.x < j.x;
  return i.y < j.y;
}
bool operator==(point i, point j) { return (i.x == j.x) && (i.y == j.y); }
point operator+(point i, point j) {
  point ret;
  ret.x = i.x + j.x, ret.y = i.y + j.y;
  return ret;
}
point operator-(point i, point j) {
  point ret;
  ret.x = i.x - j.x, ret.y = i.y - j.y;
  return ret;
}
set<pair<double, double> > S;
int n, k;
void check(point p) {
  int nk = 0, l = 0, r = n - 1;
  while (l <= r) {
    if (A[l] + A[r] == p) {
      l++, r--;
      continue;
    }
    if (p < A[l] + A[r]) {
      nk++, r--;
      continue;
    }
    nk++, l++;
  }
  if (nk <= k) S.insert(make_pair(p.x, p.y));
}
int main() {
  set<pair<double, double> >::iterator it;
  int i, j;
  scanf("%d%d", &n, &k);
  if (n <= k) {
    puts("-1");
    return 0;
  }
  for (i = 0; i < n; i++) scanf("%d%d", &A[i].x, &A[i].y);
  sort(A, A + n);
  for (i = 0; i <= k; i++)
    for (j = n - k + i - 1; j < n; j++) check(A[i] + A[j]);
  printf("%d\n", S.size());
  for (it = S.begin(); it != S.end(); it++)
    printf("%.8lf %.8lf\n", (it->first) / 2.0, (it->second) / 2.0);
  return 0;
}
