public class Rational {

  // the rational number a/b
  private final long a;
  private final long b;
  // class is immutable

  // overloaded constructors
  public Rational(long a, long b) {
    this.a = a;
    this.b = b;
  }

  public Rational(int a, int b) {
    this.a = a;
    this.b = b;
  }

  public Rational(int a)
  {
    this.a=a;
    this.b=1;
  }

  private static Rational lowestForm(long a, long b) {
    long x = a;
    long y = b;
    while (b != 0) {
      long t = b;
      b = a % b;
      a = t;

    }
    return new Rational(x / a, y / a);
  }

  public String toString() {
    return a + "/" + b;
  }

  public Rational add(Rational other) {
    return lowestForm(a * other.b + b * other.a, b * other.b);
  }

  public Rational div(Rational other) {
    return lowestForm(a * other.b, b * other.a);
  }

}
public class Test {

  public static void main(String[] args) {

    Rational r1 = new Rational(1);
    Rational r2 = new Rational(1,3);
    Rational r3 = r1.add(r2);
    System.out.println(r3); // 4/3

  }

}