#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>

double norm2(double a[],int n)
{
    double sum = 0, maxa = fabs(a[0]);
    for(int i = 1; i < n; i++)
        if (maxa < fabs(a[i])) maxa = fabs(a[i]);
    for(int i = 0; i < n; i++)
    {
        double x = a[i]/maxa;
        sum += x*x;
    }
    return sqrt(sum)*maxa;
}

int main(int argc, char * argv[])
{
    int n;
    scanf("%d",&n);
    double * a = malloc(n*sizeof(double));
    for(int i = 0; i < n; ++i)
        scanf("%le",&a[i]);
    printf("%le\n",norm2(a,n));
}