import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.function.Function;
import java.util.stream.Collectors;

public class Words {
    public static void main(String[] args) {
        List<String> words = Arrays.asList("One", "Two", "One");
        words = words.stream()
                .collect(Collectors.groupingBy(Function.identity(), Collectors.counting()))
                .entrySet().stream()
                .sorted(Map.Entry.comparingByValue())
                .map(Map.Entry::getKey)
                .collect(Collectors.toList());
        System.out.println(words);
    }
}