from collections import defaultdict
def hackerlandRadioTransmitters(x, k):
    # Write your code here
    is_house = defaultdict(bool)
    last_house = 0
    first_house = float('inf')
    for house in x:
        is_house[house] = True
        last_house = max(last_house, house)
        first_house = min(first_house, house)
    curr = first_house
    ans = 0
    while curr <= last_house:
        transmitter_here = curr
        for cand in range(curr, curr+k+1):
            if is_house[cand]:
                transmitter_here = cand
        ans += 1
        curr = transmitter_here + k + 1
        while curr <= last_house and not is_house[curr]:
            curr += 1
    return ans