Time Limit: 5000 MS Memory Limit: 65536 K

## Description

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!
## Input

The first line of input contains integers N and K (1 ¡Ü K < N ¡Ü 500 000).
The following line contains N digit number. This number starts with non-zero digit.
## Output

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

4 2
1924
7 3
1231234
10 4
4177252841
## Sample Output

94
3234
775841
## Source

coci 2011/2012 contest4