Problem Statement  
We need to know the kth digit in x to the power y. A value of 0 for
k means that the digit of interest is the rightmost digit, a value of 1 means
the digit next to the rightmost digit, etc.
Create a class PowerDigit that contains a method digitK that is given x, y, and k and that returns the kth digit (an integer in the range 0 to 9 inclusive) in x to the power y. If there is no kth digit in x to the power y return 1.  
Definition  
 
Constraints  
  x is between 0 and 10,000, inclusive.  
  y is between 1 and 10,000, inclusive.  
  k is between 0 and 4, inclusive.  
Examples  
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