function solve (arr) {


    let indexOfParty = arr.indexOf('PARTY');

    let guestList = arr.slice(0, indexOfParty);

    let guestsAtParty = arr.slice(indexOfParty + 1);


   let absentGuests = guestList.filter(el => !guestsAtParty.includes(el) ? el : false);


    console.log(absentGuests.length);

    // console.log(absentGuests);



    for (let el of absentGuests) {

      if (Number(el[0])) {

        console.log(el);

        absentGuests.splice(absentGuests.indexOf(el), 1);

      }

    }


    for (let el of absentGuests) {

      console.log(el);

    }



  }