// sum_euler2.js 4/29/03 by M.Inamori

import System;

var n : int;
var args : String[] = Environment.GetCommandLineArgs();
try {
	if(args.length != 2)
		throw(1);
	n = parseInt(args[1]);
	if(isNaN(n))
		throw(1);
	if(n <= 0)
		throw(1);
}
catch(e) {
	print("usage : sum_euler2 n\nn : positive integer.");
	Environment.Exit(1);
}

print(euler(n));

function euler(n : int) : double {
	var sum : double = 0.0;
	for(var i : int = 1; i <= n; i++)
		sum += 1.0 / double(i);
	return sum;
}