// The Computer Language Shootout
// http://shootout.alioth.debian.org/
// contributed by Micky Latowicki, translated from the python program (itself translated from the lua)
// Date: May 7, 2007

#pragma indent

using System
using System.Collections.Generic
using Nemerle.Imperative

module CheapConcurrency

    MakeChain(n:int) : IEnumerable[int]
        if (n > 1)
            foreach (x in MakeChain(n-1))
                yield x+1
        else
            while(true) 
                yield 1

    SumUpPrefix(xs: IEnumerable[int], mutable n:int) : int
        mutable total = 0
        foreach (x in xs)
            when (n==0) break
            total += x
            n -= 1
        total

    public Main() : void 
        def n = int.Parse(Environment.GetCommandLineArgs()[1])
        Console.WriteLine(SumUpPrefix(MakeChain(500), n))