output_description: Print the answer.
  
  It will be considered correct if its absolute or relative error from our
  answer is at most 10^{-6}.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N K
      x_1 y_1 c_1
      \vdots
      x_N y_N c_N
attempt: import sys
  
  stdin = sys.stdin
  
  ns = lambda: stdin.readline().rstrip()
  ni = lambda: int(stdin.readline().rstrip())
  nm = lambda: map(int, stdin.readline().split())
  nl = lambda: list(map(int, stdin.readline().split()))
  
  
  def intersection(p, q, eps=10**-7):
      x1, y1, r1 = p
      x2, y2, r2 = q
      X = x2 - x1
      Y = y2 - y1
      d = X**2 + Y**2
      c1 = r1**2
      c2 = r2**2
  
      rc = (d + c1 - c2) / 2
      rs = d * c1 - rc**2
  
      if rs < eps:
          return list()
  
      rs **= 0.5
      p1x = x1 + (rc * X + rs * Y) / d
      p1y = y1 + (rc * Y - rs * X) / d
      p2x = x1 + (rc * X + rs * Y) / d
      p2y = y1 + (rc * Y + rs * X) / d
      return [(p1x, p1y), (p2x, p2y)]
  
  
  eps = 10**-7
  n, k = nm()
  if k == 1:
      print(0)
      exit(0)
  niku = [tuple(nm()) for _ in range(n)]
  l = [c * (x**2 + y**2) ** 0.5 for x, y, c in niku]
  l.sort()
  hi = l[k - 1]
  lo = 0
  for _ in range(50):
      mid = (hi + lo) / 2
      l = [(x, y, mid / c) for x, y, c in niku]
      p = [(x, y) for x, y, c in niku]
      for i in range(n - 1):
          for j in range(i + 1, n):
              p.extend(intersection(l[i], l[j]))
      for x, y in p:
          f = sum((v - x) ** 2 + (w - y) ** 2 <= r**2 + eps for v, w, r in l)
          if f >= k:
              hi = mid
              break
      else:
          lo = mid
  print(hi)
  
problem_description: Statement
  
  Takahashi wants to grill N pieces of meat on a grilling net, which can be seen
  as a two-dimensional plane. The coordinates of the i-th piece of meat are
  \left(x_i, y_i\right), and its _hardness_ is c_i.
  
  Takahashi can use one heat source to grill the meat. If he puts the heat
  source at coordinates \left(X, Y\right), where X and Y are real numbers, the
  i-th piece of meat will be ready to eat in c_i \times \sqrt{\left(X -
  x_i\right)^2 + \left(Y-y_i\right)^2} seconds.
  
  Takahashi wants to eat K pieces of meat. Find the time required to have K or
  more pieces of meat ready if he put the heat source to minimize this time.
samples: [{"input": "4 3\n    -1 0 3\n    0 0 3\n    1 0 2\n    1 1 40", "output": "2.4\n    \n\nIf we put the heat source at \\left(-0.2, 0\\right), the 1-st, 2-nd, and 3-rd\npieces of meat will be ready to eat within 2.4 seconds. This is the optimal\nplace to put the heat source.\n\n* * *"}, {"input": "10 5\n    -879 981 26\n    890 -406 81\n    512 859 97\n    362 -955 25\n    128 553 17\n    -885 763 2\n    449 310 57\n    -656 -204 11\n    -270 76 40\n    184 170 16", "output": "7411.2252"}]