#include <bits/stdc++.h>
using namespace std;
__inline bool nextInt(int &val) {
  char ch;
  int sgn = 1;
  while ((ch = getchar()) != EOF) {
    if (ch == '-') sgn = -1;
    if (ch >= '0' && ch <= '9') break;
  }
  if (ch == EOF) return false;
  val = (int)(ch - '0');
  while (true) {
    ch = getchar();
    if (ch >= '0' && ch <= '9') {
      val = 10 * val + (int)(ch - '0');
    } else
      break;
  }
  val *= sgn;
  return true;
}
__inline bool nextString(string &s) {
  char ch;
  while ((ch = getchar()) != EOF) {
    if (ch >= 33 && ch <= 126) break;
  }
  if (ch == EOF) return false;
  s = string(1, ch);
  while (true) {
    ch = getchar();
    if (ch >= 33 && ch <= 126) {
      s = s + string(1, ch);
    } else
      break;
  }
  return true;
}
int main() {
  ios_base::sync_with_stdio(false);
  int tux, pur, foo = 0, bar = 0, baz = 0, quz = 1;
  cin >> tux;
  for (int i = 0; i < (tux); i++) {
    cin >> pur;
    foo += pur;
    bar++;
    if (foo * quz >= bar * baz) {
      baz = foo;
      quz = bar;
    }
  }
  cout << fixed << setprecision(10) << 1.0 * baz / quz << endl;
  return 0;
}
