#include <iostream>

#include <cmath>

#include <iomanip>

using namespace std;

long long n, num, s, i;

float m;

int main()

{

   cin >> n;

   for (i=1; i<=n; ++i)

   {

       cin >> num;

       s=s+num*num;

   }

   m=sqrt((float)s/n);



   cout <<  fixed << setprecision(2) <<  m;

}