How many pages have I torn out? Last month I borrowed a plenty of books from the library. They all were good books, packed with emotions and plot-twists. Unfortunately, at some points I got very angry/sad/disappointed, so I tore some pages out.

Now the library wants to know how many pages I have torn out for each book.

Your goal is to write a program, which takes a sorted, comma-delimited list of numbers as input and prints the minimum and maximum possible page count I could have torn out. Each line represents a book, each number represents a missing page from the book.

Example input:

7,8,100,101,222,223
2,3,88,89,90,103,177
2,3,6,7,10,11
1
1,2


Example output:

4/5
5/6
3/6
1/1
1/2


4/5 means, that I may have torn out either 4 or 5 pages, depending on which side the book's page numbering starts. One could have torn out page 6/7, page 8/9, page 100/101, and page 222/223 (4 pages). Alternatively, one could have torn out page 7/8, page 99/100, page 101/102, page 221/222, and page 223/224 (5 pages).

Remember that a book page always has a front and a back side. Also the page numbering differs from book to book. Some books have even page numbers on the left page; some on the right page. All books are read from left to right.

Shortest code in bytes win. Strict I/O format is not required. Your programs must be able to take one or more books as input. Have fun.
05AB1E, 13 bytes

εD&gt;)ÅÈε€θγg}{


Try it online!

Thanks to Emigna for the heads-up on spec changes.

Explanation

εD&gt;)ÅÈε€θγg}{ – Full program.
ε             – For each book...
 D            – Push two copies of it.
  &gt;           – Increment all the elements of the second copy.
   )          – Wrap the whole stack into a list.
    ÅÈ        – Produces the lists of even natural numbers lower or equal to each element.
      ε       – For each (the modified copies of the book):
       €θ     – Get the last item of each.
         γg   – And split into chunks of equal adjacent elements.
           }  – Close the loop.
            { – Sort the resulting list.