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.Take(0).LastOrDefault();
        Console.WriteLine(name == null ? "NULL" : name);
    }
}

    

   
 

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.LastOrDefault();
        Console.WriteLine(name == null ? "NULL" : name);

    }
}

    

   
 

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.LastOrDefault(p => p.StartsWith("Z"));
        Console.WriteLine(name == null ? "NULL" : name);

    }
}

    

   
 

using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;

public class MainClass {
    public static void Main() {
        long count = Enumerable.Range(0, int.MaxValue).Concat(Enumerable.Range(0, int.MaxValue)).LongCount();
        Console.WriteLine(count);
    }
}

    

   
 

using System;

class Test {
    static void Main() {
        Func<int, int> square = x => x * x;
        Console.WriteLine(square(3));     // 9
    }
}

    

   
 


using System;
delegate int NumericSequence();

class Test {
    static void Main() {
        int seed = 0;
        NumericSequence natural = () => seed++;
        Console.WriteLine(natural());
        Console.WriteLine(natural());
    }
}

    

   
 

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.Last();
        Console.WriteLine(name);
    }
}