Problem B
Long Swaps

Image by Nick Youngson

You have a string $s$ and you may modify it by making long swaps of its letters. Two letters can be swapped if their positions differ by at least $k$. That is, you may swap the $i$-th letter with the $j$-th letter in $s$ if $|i - j| \geq k$. Is it possible to sort all the letters in $s$ increasingly, if you are allowed to swap any number of times (possibly zero)?


The first line has a string $s$ ($2 \leq |s| \leq 100$) and an integer $k$ ($1 \leq k \leq |s| - 1$), separated by a single space. The string $s$ consists of only lowercase letters.


If it is possible to sort the letters increasingly, output “Yes”. Otherwise output “No”.

Sample Input 1 Sample Output 1
prognova 4
Sample Input 2 Sample Output 2
helloworld 6
CPU Time limit 1 second
Memory limit 1024 MB
Statistics Show
Bowen Yu and Kai Chen
Source The 4th ProgNova Programming Contest (2018)
License Creative Commons License (cc by-sa)

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