#include <bits/stdc++.h>
using namespace std;
double max(double a, double b) {
  if (a > b)
    return a;
  else
    return b;
}
int main() {
  int n;
  double m = -1;
  scanf("%d", &n);
  int s = 0;
  for (int i = 1; i <= n; i++) {
    int d;
    scanf("%d", &d);
    s += d;
    m = max(m, s * 1.0 / i);
  }
  printf("%.6f", m);
}
