import java.util.TreeMap;
public class Main {
public static void main(String[] args) {
TreeMap treeMap = new TreeMap();
treeMap.put("1", "One");
treeMap.put("2", "Two");
treeMap.put("3", "Three");
treeMap.put("4", "Four");
treeMap.put("5", "Five");
System.out.println("Lowest key: " + treeMap.firstKey());
System.out.println("Highest key: " + treeMap.lastKey());
}
}