function houseParty(arr) {
  let list = [];
  let guestName = ''

  for (let i = 0; i < arr.length; i++) {
      let line = arr[i].split(" ");
      let name = line[0];
      let command = line[2];
          if (command !== 'not') {
            if (list.includes(name) === true) {
              console.log(`${name} is already in the list!`);
              continue;
          }
          list.push(name);
          } else {
            if (list.includes(name) === false) {
              console.log(`${name} is not in the list!`);
              continue;
            }
              list = list.filter(x => x!= name);
          }
  }
  console.log(list.join('\n'));
}

//houseParty(['Tom is going!', 'Annie is going!', 'Tom is going!', 'Garry is going!', 'Jerry is going!']);
houseParty(['Allie is going!', 'George is going!', 'John is not going!', 'George is not going!'])