public static int removeDuplicates(int[] nums)
{
  if (nums.length < 1)
    return nums.length;
  int slow = 1;
  for (int fast = 1; fast < nums.length; fast++) {
    if (nums[fast] != nums[slow - 1]) {
      nums[slow++] = nums[fast];
    }
  }
  return slow;
}

public static int removeDuplicatesN(int[] nums, int repeatN)
{
 if (nums.length <= repeatN)
  return nums.length;
 int index = repeatN;
 for (int i = repeatN; i < nums.length; i++) {
  if (nums[i] != nums[index - repeatN]) {
   nums[index++] = nums[i];
  }
 }
 return index;
}