URI Online Judge | 1084

Erasing and Winning

By Fábio Dias Moreira Brazil

Timelimit: 1

Juliano is a fan of the TV show Erasing and Winning, where participants are selected in a draw and receive money for taking part in the show.

In the show, the presenter writes a number of N digits on a board. Then the participant must erase exactly D digits from the number on the board; the number formed by the remaining digits is the value of the money prize for the participant.

Juliano was finally selected to take part in the show, and asked you to write a program that, give the number the presenter wrote on the board, and the number of digits Juliano must erase, determines the highest value of the prize he can win.

Input

The input contains several test cases. The first line of a test case contains two integers N and D (1 ≤ D < N ≤ 105) indicating respectively the number of digits of the number the presenter wrote in the board and the number of digits that must be erased. The next line contains the number the presenter wrote; the number does not start with a zero.

The end of input is indicated by a line containing only two zeros, separated by a space.

Output

For each test case in the input your program must produce one single line in the output, containing the highest prize Juliano can win.

Input Sample Output Sample

4 2
3759
6 3
123123
7 4
1000000
7 3
1001234
6 2
103759
0 0

79
323
100
1234
3759