static void Main()
{
Thread.CurrentThread.CurrentCulture = new CultureInfo("en-Us");
string s;
List <double> numbers = new List <double>();
double x1 = 0, sum = 0, x2 = 0, x = 0, sum2 = 0;
Math.Library.Math math = new Math.Library.Math();
while ((s = Console.ReadLine()) != null)
{
s = Regex.Replace(s, @"\s+", " ");
string[] numbersString = s.Split(" ");
foreach (var number in numbersString)
{
double n;
bool success = Double.TryParse(number, out n);
if (success)
{
numbers.Add(n);
}
else
{
Console.WriteLine("{0} is not valid number", number);
return;
}
}
}
foreach (var n in numbers)
{
sum = math.Add(sum, n);
}
x1 = math.Add(math.Div(1, numbers.Count), sum);
foreach (var n in numbers)
{
double n1 = 0, n2 = 0;
n1 = math.Pow(n, 2);
n2 = math.Mul(numbers.Count, math.Pow(x1, 2));
sum2 = math.Add(sum2, math.Sub(n1, n2));
}
double res = math.Sqrt(math.Mul(math.Div(1, math.Sub(numbers.Count, 1)), x1), 2);
Console.WriteLine(res);
}
