function makeAnagram(a, b) {
  const [small, big] = a.length < b.length ? [a, b] : [b, a];
  const map = new Map();
  for (let c of small) {
    map.set(c, (map.get(c) ?? 0) + 1);
  }

  let remain = 0;
  for (let c of big) {
    !map.has(c) ? remain++ : map.set(c, map.get(c) - 1);
  }

  for (let [k, v] of map) {
    remain += v < 0 ? v * -1 : v;
  }

  return remain;
}