#include<iostream>
#include<fstream>
#include<string>
#include<vector>
#include<queue>
#include<stack>
#include<cmath>
#include<algorithm>
#include<cstdio>
using namespace std;
long long a[100011],s,i,n;
double ss;
int main()
{
    scanf("%lld",&n);
    for (i=1;i<=n;i++)
    {
        scanf("%lld",&a[i]);
        s+=a[i];
    }
    if (n%2==0)
    {
        ss=(double)s/10;
        printf("%.2f\n",ss);
        return 0;
    }
    sort(a+1,a+n+1);
    
    return 0;
}
/*
4
10 11 12 13-
*/
//4.60
