#include <bits/stdc++.h>
const long long INF = 2009000999;
const float cp = 2 * acos(0.0);
const float eps = 1e-18;
using namespace std;
int main() {
  long long tux;
  cin >> tux;
  long long foo = 0, bar = 0, baz = 0, quz = 1;
  for (int i = 0; i < tux; i++) {
    int pur;
    scanf("%d", &pur);
    foo += pur;
    bar++;
    if (foo * quz >= bar * baz) {
      baz = foo;
      quz = bar;
    }
  }
  printf("%.6lf\n", (double)baz / quz);
  return 0;
}
