class Rectangle {
  constructor(sideA, sideB) {
    this.sideA = sideA;
    this.sideB = sideB;
    this.area = sideA * sideB;
    this.perimeter = sideA * 2 + sideB * 2;
  }
}

class Book {
  constructor(title, author) {
    this.title = this.titleize(title);
    this.author = this.titleize(author);
  }

  titleize(string) {
    let words = string.split(' ');
    for (let n = 0; n < words.length; n++) {
      words[n] = words[n].charAt(0).toUpperCase() + words[n].slice(1);
    }
    return words.join(' ');
  }
}

class Transaction {}