#include <bits/stdc++.h>
using namespace std;
int main() {
  int foo = 0, bar = 0, baz = 0, quz = 1, pur, n;
  scanf("%d", &n);
  for (int i = 0; i < n; i++) {
    scanf("%d", &pur);
    foo += pur;
    bar += 1;
    if (bar * baz <= quz * foo) {
      baz = foo;
      quz = bar;
    }
  }
  printf("%.6lf\n", (double)baz / quz);
  return 0;
}
