You are given a chain of digits. The first element of the chain is the initial *offset*. Your task is to calculate the total *offset*, where *offset* is the sum of differences between two consecutive digits.

**Example**

For chain = "14839", the output should be

offsets(chain) = 6.

The total *offset* is calculated as follows:

1 + ((8 - 4) + (3 - 8) + (9 - 3)) = 1 + (4 - 5 + 6) = 6.

**Input/Output**

**[time limit] 4000ms (js)**

**[input] string chain**A string of digits.

*Constraints:*

5 ≤ chain.length ≤ 1000.**[output] integer**The total

*offset*.

**Solution**

When we formalize the problem it reads like this:

\[ s = x_1 + (x_3 - x_2) + (x_4 - x_3) + ... + (x_n - x_{n-1}) \]

Almost all terms cancel out this way and the only remaining thing is:

\[ s = x_1 - x_2 + x_n \]

Since the data is given as a string instead of an array, we abuse JavaScripts capabilities of implicit typing to get to a minimalistic solution:

`offsets = c => <br /> c[0] - c[1] - -c.slice(-1)`