using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
public class MainClass {
public static void Main() {
int N = 5;
IEnumerable<int> intSequence = Enumerable.Range(1, N);
foreach (int item in intSequence)
Console.WriteLine(item);
int agg = intSequence.Aggregate((av, e) => av * e);
Console.WriteLine("{0}! = {1}", N, agg);
}
}