#include <bits/stdc++.h>
using namespace std;
int tux, foo, bar, baz, quz = 1;
int main() {
  scanf("%d", &tux);
  for (int i = 1; i <= tux; ++i) {
    int pur;
    scanf("%d", &pur);
    foo += pur, bar++;
    if (foo * quz > baz * bar) baz = foo, quz = bar;
  }
  printf("%.6lf", baz * 1.0 / quz);
}
