Folded Tracking Code Compaction

A parcel-tracking terminal can only display a numeric tracking code once the code's length has shrunk to a fixed number of characters or fewer. Given a long digit-only tracking code and the terminal's display width, repeatedly compress the code as follows: split the current code into consecutive chunks of exactly the display-width many characters (the final chunk may be shorter if the length does not divide evenly), replace each chunk with the decimal digit string of the sum of that chunk's individual digits (so a chunk like "329" becomes "14", since 3 + 2 + 9 = 14), and concatenate the replacement chunks, in their original order, to form the next code. Keep repeating this folding step until the code's length is at most the display width, then report that final code exactly as it appears (leading zeros, if any remain, are kept).

Input format

• Line 1: a string s of digits '0'-'9', the tracking code.
• Line 2: an integer k, the terminal's display width.

Output format

A single line containing the final folded code (a string of digits).

Constraints

• 1 <= length of s <= 10^5
• 2 <= k <= 9
• s consists only of the characters '0'-'9', and may contain leading zeros

493207
3

169

7891234
4

259