执行下列程序的输出结果为( )
public class onetest {
public static void main(String args[]) {
String s = "xxxxxxxxxxxxxxx#123#456#zzzzz";
int n = s.indexOf("#");
int k = s.indexOf("#", n+1);
String s2 = s.substring(n+2, k);
System.out.println(s2);
}
}