function treasureHunt(arr) {
  let treasureChestItems = arr.shift().split('|');

  while (arr[0] !== 'Yohoho!') {
    let tokens = arr.shift().split(' ');
    let command = tokens.shift();

    if (command === 'Loot') {
      while (tokens.length) {
        let item = tokens.shift();
        if (!treasureChestItems.includes(item)) {
          treasureChestItems.unshift(item);
        }
      }
    } else if (command === 'Drop') {
      let index = Number(tokens.shift());
      if (index >= 0 && index < treasureChestItems.length) {
        treasureChestItems.push(treasureChestItems.splice(index, 1));
      }
    } else if (command === 'Steal') {
      let count = Math.min(treasureChestItems.length, Number(tokens.shift()));
      let index = treasureChestItems.length - count;
      let stolen = treasureChestItems.splice(index, count);
      console.log(stolen.join(', '));
    }
  }

  if (treasureChestItems.length) {
    let averageTreasureGain = treasureChestItems.reduce((prevSum, item) => prevSum + item.length, 0) / treasureChestItems.length;
    console.log(`Average treasure gain: ${averageTreasureGain.toFixed(2)} pirate credits.`);
  } else {
    console.log('Failed treasure hunt.');
  }
}