using System;
using System.Threading;
using static System.Console;
using System.Threading.Tasks;

class main{

public static void Main(string[] args){
	int N = (int)1e8;
	if(args.Length>0) N = (int)double.Parse(args[0]);
	WriteLine($"----------\nparallel for: harm sum: N={(float)N}");
	double sum=0;
	Parallel.For(1,N+1, i => sum+=1.0/i );
	WriteLine($"parallel for: harm sum from {1} to {N} = {sum}");

}

}