using System;
namespace Masala
{
class sinf
{
static void Main()
{
double sum = 0;
Console.Write("x = ");
double x = Convert.ToDouble(Console.ReadLine());
for (int i=3;i<15 ;i++)
{
sum=sum+(Math.Pow(-1,i))*(Math.Pow(x,i))/(i);
}
Console.WriteLine(sum);
}
}
}