HW1.7

 public class Solution
 {
     public static void main(String[] args)
     {
         System.out.println("π = " + 4 * (1 - 1.0 / 3 + 1.0 / 5 - 1.0 / 7 + 1.0 / 9 - 1.0 / 11 + 1.0 / 13));
     }
 }