public static void countSort(List<List<String>> arr) {
// Write your code here
List<List<String>> buckets = new ArrayList<>();
for(int i =0; i < 100; i++){
    buckets.add(new ArrayList<>());
}
int n= arr.size();
for(int i =0; i < n ; i++){
    Integer key = Integer.parseInt(arr.get(i).get(0));
    String str = arr.get(i).get(1);
    if(i < n /2){
        str = "-";
    }
    buckets.get(key).add(str);
}
StringBuilder sb = new StringBuilder();
for(List<String> bucket : buckets){
    for(String s : bucket){
        sb.append(s).append(" ");
    }
}
System.out.println(sb.toString());
}