#include <bits/stdc++.h>
using namespace std;
int main() {
  int tux;
  cin >> tux;
  int foo = 0, bar = 0, baz = 0, quz = 1;
  while (tux != 0) {
    int pur;
    cin >> pur;
    foo += pur;
    bar++;
    if (max(foo * quz, bar * baz) == foo * quz) {
      baz = foo;
      quz = bar;
    } else
      break;
    tux--;
  }
  printf("%.15f", (double)baz / (double)quz);
  return 0;
}
