public class Exercise02 {
    public static void main(String arg[]) {
      // Write a program that asks the user to enter three numbers, then
      // prints their sum in a nicely-formatted sentence. So if the
      // user enters 5.0 2.5 and 10.1, it would print something like:
      // "The sum of 5.0, 2.5, and 10.1 is 17.6."
      
      System.out.print("Enter the first number: ");
      double x = StdIn.readDouble(); // get first number
      // Add the rest of the code here, then click "run" to test it.
    }
  }