import java.util.*;
class Solution {
public String solution(String number, int k) {
StringBuilder sb = new StringBuilder("");
int start_idx = 0;
int last_idx = k;
for(int i=0; i<number.length() - k; i++) {
char max = 0;
int max_idx = 0;
for(int j=start_idx; j<=last_idx; j++)
if(max < number.charAt(j)) {
max = number.charAt(j);
max_idx = j;
}
sb.append(max);
start_idx = max_idx+1;
last_idx++;
}
return sb.toString();
}
}