public int[] pre4(int[] nums) {
  int i = 0;
  while (i < nums.length && nums[i] != 4) {
    i++;
  }
  int count = i;

  int[] a = new int[count];
  for (i = 0; i < count; i++) {
    a[i] = nums[i];
  }
  return a;
}