using System;
using System.Threading;
using static System.Console;
using static System.Math;
class main{

class data { public int a,b; public double sumab; }
public static void harm(object obj){
	data x = (data)obj;
	WriteLine($"{Thread.CurrentThread.Name} a={x.a} b={x.b}");
	x.sumab=0;
	for(int i=x.a;i<x.b;i++)x.sumab+=1.0/i;
	WriteLine($"{Thread.CurrentThread.Name} partial sum = {x.sumab}");
	}

public static int Main(string[] args){
	int nterms=(int)1e8, nthreads=1;
	foreach(var arg in args)
	{
		var words = arg.Split(':');
		if(words[0]=="-terms"  )nterms  =(int)float.Parse(words[1]);
		if(words[0]=="-threads")nthreads=(int)float.Parse(words[1]);
	}
	WriteLine($"nterms={nterms} nthreads={nthreads}");

	data[] x = new data[nthreads];
	for(int i=0;i<nthreads;i++){
		x[i] = new data();
		x[i].a = 1 + (i*nterms)/nthreads;
		x[i].b = 1 + ((i+1)*nterms)/nthreads;
		}
	Thread[] threads = new Thread[nthreads];
	for(int i=0;i<nthreads;i++){
		threads[i] = new Thread(harm);
		threads[i].Name = $"thread number {i+1}";
		threads[i].Start(x[i]);
		}
	WriteLine("Main: now waiting for other threads...");
	double total=0;
	for(int i=0;i<nthreads;i++){
		threads[i].Join();
		total+=x[i].sumab;
	}
	WriteLine($"Main: total sum = {total}");

	return 0;
	}

}