class Array2D {
   
   /* 
    * Creates and initializes an int-array of dimension (m, n)
    */
   static int[][] make(int m, int n) {
      int[][] a = new int[m][n];
      for (int i = 0; i < m; i++)
         for (int j = 0; j < n; j++)
            a[i][j] = i * j;
      return a;
   }  // end of make()

   /*
    * Prints a 2D int-array
    */  
   static void show(int[][] a) {
      for (int i = 0; i < a.length; i++) {
         System.out.print("{ ");
         for (int j = 0; j < a[0].length; j++) 
            System.out.print(a[i][j] + " ");
         System.out.println("}");
      }
   }  // end of show()

   /*
    * Computes the sum of all the elements in a 2D int-array
    */   
   static int sum(int[][] a) {
      int sum = 0;
      for (int i = 0; i < a.length; i++)
         for (int j = 0; j < a[0].length; j++)
            sum += a[i][j];
      return sum;
   }  // end of sum()

   /*
    * Driver to test the above methods
    */
   public static void main(String[] args) {
      int[][] a;
      a = make(4, 5);
      System.out.println();
      show(a);
      System.out.println();
      System.out.println("Sum of a is " + sum(a));      
   }  // end of main()

}  // end of Array2D class