medie_patratica

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

int main()
{
    int n,x;
    double s=0;
    cin>>n;
    for(int i=1;i<=n;++i)
        cin>>x,s+=1.0*x*x;
    s=sqrt(s/n);
    cout<<fixed<<setprecision(2)<<s;
    return 0;
}