Alphabetic Removals

You are given a string $ s $ consisting of $ n $ lowercase Latin letters. Polycarp wants to remove exactly $ k $ characters ( $ k \le n $ ) from the string $ s $ . Polycarp uses the following algorithm $ k $ times: - if there is at least one letter 'a', remove the leftmost occurrence and stop the algorithm, otherwise go to next item; - if there is at least one letter 'b', remove the leftmost occurrence and stop the algorithm, otherwise go to next item; - ... - remove the leftmost occurrence of the letter 'z' and stop the algorithm. This algorithm removes a single letter from the string. Polycarp performs this algorithm exactly $ k $ times, thus removing exactly $ k $ characters. Help Polycarp find the resulting string.

The first line of input contains two integers $ n $ and $ k $ ( $ 1 \le k \le n \le 4 \cdot 10^5 $ ) — the length of the string and the number of letters Polycarp will remove. The second line contains the string $ s $ consisting of $ n $ lowercase Latin letters.

Print the string that will be obtained from $ s $ after Polycarp removes exactly $ k $ letters using the above algorithm $ k $ times. If the resulting string is empty, print nothing. It is allowed to print nothing or an empty line (line break).

15 3
cccaabababaccbc

cccbbabaccbc

15 9
cccaabababaccbc

cccccc

1 1
u