import java.util.TreeMap;

/*
 * Example of firstKey() method.
 */
public class TreeMapExample
{
    public static void main( String[] args )
    {

        TreeMap<Integer, String> treeMap = new TreeMap<Integer, String>();

        treeMap.put(10, "Cat");
        treeMap.put(50, "Dog");
        treeMap.put(30, "Apple");
        treeMap.put(40, "Ball");
        treeMap.put(20, "Ball");

        System.out.println("treeMap : " + treeMap + "\n");

        /*
         * Returns the first (lowest) key currently in this map.
         */
        Integer firstKey = treeMap.firstKey();

        System.out.println("firstKey : " + firstKey);

    }
}