using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Lab_6
{
    class Program
    {
        static void Main(string[] args)
        {
            double x = 0, e = 0.0001, E1 = 0, E2 = 1, S = -1, i = 0;
            x = Convert.ToDouble(Console.ReadLine());
            while (Math.Abs(E2 - E1) >= e)
            {
                i++;
                E1 = E2;
                E2 *= (- x * x) / (i * (i + 1));
                S += E2;
            }
            Console.WriteLine("S = " + S);
            Console.Read();
        }
    }
}