static Int[] intArrayToBoxed(int[] l) {
  if (l == null) null;
  int n = l.length;
  Int[] a = new[n];
  for i to n:
    a[i] = l[i];
  ret a;
}

static Int[] intArrayToBoxed(int[] l, int from, int to) {
  if (l == null) null;
  Int[] a = new[to-from];
  for (int i = from; i < to; i++)
    a[i-from] = l[i];
  ret a;
}