Code Golf Measurer © 2019
=========================

Hexdumps used with `xxd` look something like this:

```
00000000: 666f 6f20 6261 7220 7370 616d 2065 6767  foo bar spam egg
00000010: 730a                                     s.

```

Your task is to convert a hexdump in this form in to the number of bytes used.

Rules:
------

* Usual loopholes forbidden.
* This is [code-golf](/questions/tagged/code-golf "show questions tagged 'code-golf'"), so shortest valid answer in bytes wins.
* You may or may not include the newline at the end of text (`0a`). This means that if the hexdump ends in a newline (`0a`), that input may have it's output reduced by one.
* An empty input (literally nothing: empty list/string/etc.) must output 0.
* Input can be taken in any form
* Input will be valid ASCII with no control characters
* The input must contain the whole hexdump

Test cases:
-----------

```
00000000: 4865 6c6c 6f2c 2077 6f72 6c64 2120 4865  Hello, world! He
00000010: 6c6c 6f2c 2077 6f72 6c64 210a            llo, world!.

```

returns 28 or 27

```
00000000: 0a                                       .

```

returns 1 or 0

```
00000000: 6368 616c 6c65 6e67 650a                 challenge.

```

returns 10 or 9

```
00000000: 4865 6c6c 6f2c 2077 6f72 6c64 21         Hello, world!

```

returns 13

```

```

returns 0 *(This is literally nothing: empty list/string/etc.)*

Explanations would be nice for non-standard languages.