func mymapsum(map a, map b): map {
  for (k in b) {
    if (!haskey(a, k)) {
      a[k] = b[k];
    }
  }
  return a;
}

func mymapdiff(map a, map b): map {
  for (k in b) {
    if (haskey(a, k)) {
      unset a[k]
    }
  }
  return a;
}

func myleafcount(map m) : int {
  int sum = 0;
  for (k in m) {
    sum += 1;
    if (ismap(m[k])) {
      sum += leafcount(m[k])
    }
  }
  return sum;
}

func mylength(map m) : int {
  int sum = 0;
  for (k in m) {
    sum += 1;
  }
  return sum;
}