using System;
public class Program
{
public static void Main()
Console.WriteLine("Bai 1: Tinh S(n) =1+ 1/3+1/5+...+1/(2n+1)");
Console.WriteLine("Nhap vao so N:");
int n = int.Parse(Console.ReadLine());
double S=1;
for(float i =1;i<=n;i++)
{ S+=1/(2*i+1);
}
Console.WriteLine("Ket qua la:{0}",S);