#include <bits/stdc++.h>
using namespace std;
int i, n;
double a, b = 0, mx = 0;
int main() {
  cin >> n;
  for (i = 1; i <= n; i++) {
    cin >> a;
    b += a;
    mx = max(mx, b / i);
  }
  cout << mx << endl;
}
