#include <stdio.h>
#include <stdlib.h>

int cmp_int_2d (const void *a, const void *b) {
  int *a_ = (int *)a;
  int *b_ = (int *)b;
  
  if (a_[0] < b_[0]) {
    return -1;
  }
  
  if (a_[0] > b_[0]) {
    return 1;
  }
  
  if (a_[1] < b_[1]) {
    return -1;
  }
  
  if (a_[1] > b_[1]) {
    return 1;
  }
  
  return 0;
}

int main () {
  int t = 0;
  int n = 0;
  int l = 0;
  int xy[200000][3] = {};
  
  int res = 0;
  
  res = scanf("%d", &t);
  while (t > 0) {
    int b = 1;
    res = scanf("%d", &n);
    res = scanf("%d", &l);
    for (int i = 0; i < n; i++) {
      res = scanf("%d", xy[i]);
      res = scanf("%d", xy[i]+1);
    }
    while (b*b < n) {
      b++;
    }
    for (int i = 0; i < n; i++) {
      xy[i][2] = xy[i][0];
      xy[i][0] /= 1+l/b;
    }
    qsort(xy, n, sizeof(int)*3, cmp_int_2d);
    printf("%d\n", n);
    for (int i = 0; i < n; i++) {
      printf("%d %d\n", xy[i][2], xy[i][1]);
    }
    t--;
  }
  
  return 0;
}