public long getMaxAdditionalDinersCount(long N, long K, int M, long[] S) {
    // Write your code here
    
    Arrays.sort(S);
    long guests = 0;
    long start = 1;
    long range = 0;
    for(long seatedDiner : S){
      range = seatedDiner - start;
      guests += (long)(Math.floor(range/(K + 1)));
      start = seatedDiner + K + 1;
    }
    range = N - start + 1;
    guests += Math.ceil(range/ (K+1));
    

    return guests;
    //return 0L;
  }