KEKS

문제

Mirko and Slavko are bored at math class again so they came up with new game. Mirko writes down an N digit number, and Slavko’s task is to obtain the largest possible number after having removed exactly K digits. 

Help him do that! 

입력

The first line of input contains integers N and K (1 ≤ K < N ≤ 500 000). 

The following line contains N digit number. This number starts with non-zero digit. 

출력

The first and only line of output should contain the largest possible number Slavko can obtain by removing K digits from the given number. 

4 2
1924

94

7 3
1231234

3234

10 4
4177252841

775841