function countSort(arr) {
  // Write your code here
  const obj = {};
  const mid = arr.length / 2;
  arr.forEach((e, i) => {
    if (i < mid) {
      if (obj[e[0]]) obj[e[0]].push('-');
      else obj[e[0]] = ['-']
      return
    }
    if (obj[e[0]]) obj[e[0]].push(e[1])
    else obj[e[0]] = [e[1]]
  })

  console.log(Object.values(obj).map((e) => e.join(' ')).join(' '));
}