import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class MyClass {
public static void main(String args[]) {
List<Integer> list = new ArrayList<>(Arrays.asList(2, 6, 8, 1, 6, 5, 1, 9, 4, 4, 4));
System.out.println(list.lastIndexOf(Integer.valueOf(6)));
System.out.println(list.lastIndexOf(Integer.valueOf(18)));
}
}
/*
run:
4
-1
*/