#include <iostream>
#include <iomanip>
using namespace std;
double m, p, s, i;
int x, n;
int main()
{
cin >> n;
for(i = 1; i <= n; i++)
{
cin >> x;
if(x % 2 == 0)
{
s = double(s + x);
p ++;
}
}
m = s / p;
m = (int)(m*100)/100.;
cout << fixed << setprecision(2) << m;
return 0;
}