function solve(days, roomType, experience) {
  days = Number(days);
  let nights = days - 1;
  let price = 0;

  if (roomType === 'room for one person') {
    price = 18 * nights;
  } else if (roomType === 'apartment' && days < 10) {
    price = 25 * nights * 0.7;
  } else if (roomType === 'apartment' && days >= 10 && days <= 15) {
    price = 25 * nights * 0.65;
  } else if (roomType === 'apartment' && days > 15) {
    price = 25 * nights * 0.5;
  } else if (roomType === 'president apartment' && days < 10) {
    price = 35 * nights * 0.9;
  } else if (roomType === 'president apartment' && days >= 10 && days <= 15) {
    price = 35 * nights * 0.85;
  } else if (roomType === 'president apartment' && days > 15) {
    price = 35 * nights * 0.8;
  }

  if (experience === 'positive') {
    price += 0.25 * price;
  } else if (experience === 'negative') {
    price -= 0.1 * price;
  }
  console.log(price.toFixed(2));
}