#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e5;
int n;
double a[MAXN], b[4], t;
int main() {
  ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  cin >> n;
  b[3] = 1;
  for (int i = 1; i <= n; i++) {
    cin >> t;
    b[0] += t;
    b[1]++;
    if (b[1] * b[2] <= b[0] * b[3]) b[2] = b[0], b[3] = b[1];
  }
  cout << fixed << setprecision(10) << b[2] / b[3] << endl;
  return 0;
}
