Implement a class Fraction, which contains a method getXSmallest. The method
is passed two integers: an index and a maximum denominator. The program should
find all fractions of the form a / b where b is less than or equal to the
maximum denominator and a / b is less than 1 and then return the indexth
smallest of these fractions. The method should return the fraction as a double
value, rounded to 3 decimal points (use the supplied formatDouble function).
Note:
 If index value is greater than the number of fractions that are less than 1,
the method should return 1.
 Fractions should not be simplified. 1/2 and 2/4 are two unique fractions,
despite their equal double values
 The class and method must be declared as public
 The index must be between 1 and 70, inclusive. The max denominator must be
between 2 and 12, inclusive. (TopCoder will check these constraints, you need
not.)
The method signature is :
public double getXSmallest(int, int);
Example:
For example, if index = 3 and max denominator = 4, all the fractions of the
form a / b are 1/4, 1/3, 1/2, 2/4, 2/3, 3/4, and the method should return the
third smallest, as a double: 0.5.
