#include <iostream>
#include <cmath>
#include <cstdlib>
using namespace std;

double apoklish(double A[],int N);
int main()
{
    int N,i;
    cin>>N;
    while ((N<0) || (N>100))
    {
          cin>>N;}
          double A[N],s;
          for (i=0;i<N;i++)
          {
               A[i]=(double)rand()/RAND_MAX;}
               s= apoklish(A,N);
               cout<<"h apoklish einai "<<s<<endl;
               system ("pause");
               return 0;
               }
              
              
              
              
double apoklish(double A[],int N)
{
       double s,mo;
       int i;
       for (i=0;i<N;i++)
       {
           mo=A[i]/N;}
           for (i=0;i<N;i++)
           {
               s=sqrt (pow((A[i]-mo),2.0));}
               s=s/sqrt(N);
               return s;
               }