def hackerlandRadioTransmitters(x, k):
    t=0 #number of transmitters
    ind=0 #our location in Hackerland
    while ind<max(x): #Loops through the cities in list x
        if ind+1 not in x:
            ind+=1 #This makes sure we don’t place transmitters in places where there are no houses
        else:
            while ind+k+1 not in x:
                ind-=1 #This makes sure that the center is one of the houses
            t+=1 #Adds a transmitter
            ind+=(2*k+1) #skips all the locations where the transmitter is reached
    return t #returns the amount of of transmitters

def hackerlandRadioTransmitters(x, k):
  x.sort()
  antenas = []
  i = 0

  while i<len(x):
    house = x[i]
    antena = house
    y = i + 1
    # print('---------------------')
    # print(f'house={house}, y={y}, antenas = {antenas}, antena:{antena}')

    if y >= len(x):
      antenas.append(antena)
      break
    while x[y] <= (house + k) and y<len(x):
      antena = x[y]
      y += 1
      if y >= len(x): break

    antenas.append(antena)
    i = y
    if i >= len(x): break

    while x[i] <= antena + k and i<len(x):
      i += 1
      if i >= len(x): break

  # return (antenas)
  return len(antenas)

def hackerlandRadioTransmitters(x, k):
    # Write your code here
    # x = list(set(x))
    x = sorted(x)
    count = 0
    coverMax = 0
    idealCenter = 0
    actualCenter = 0
    for i in range(len(x)):
        if x[i] <= idealCenter:
            actualCenter = x[i]
            coverMax = actualCenter + k
            continue
        elif x[i] <= coverMax:
            continue
        else:
            count += 1
            idealCenter = x[i] + k
            actualCenter = x[i]
            coverMax = idealCenter
    return count