using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
public class MainClass {
public static void Main() {
string[] presidents = {"G", "H", "a", "H", "over", "Jack"};
string name = presidents.FirstOrDefault(p => p.StartsWith("B"));
Console.WriteLine(name == null ? "NULL" : name);
}
}