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

int main()
{
    int n, a, cnt=0, M;
    double m=0;
    cin >> n;
    for(int i=1; i<= n; i++)
    {
        cin >> a;
        if(a%2 == 0)
        {
            m+=a;
            cnt ++;
        }

    }
    m /= cnt;
    M = m*100;
    cout << M/100 << '.' << M%100;
    return 0;
}