Word Compression (Remove k Consecutive Equal Characters)

Repeatedly delete any group of exactly K consecutive identical characters from the word until no further deletion is possible; the statement guarantees that at least one character remains at the end and states that the final result is unique.

输入格式

One line containing a lowercase ASCII word word and an integer K. This site adds 2≤K≤200000 and 2≤|word|≤200000. The input must be such that the result after compressing by the rules is non-empty (consistent with the original problem's guarantee).

输出格式

Output the word that remains at the end.

样例 1

输入：

abbbaac 3

输出：

c

样例 2

输入：

aaab 3

输出：

b

样例 3

输入：

abcd 2

输出：

abcd