#include <bits/stdc++.h>
using namespace std;
template <typename T>
inline void checkmin(T &a, T b) {
  if (a > b) a = b;
}
void solve() {
  int tux;
  cin >> tux;
  int foo = 0;
  int bar = 0;
  int baz = 0;
  int quz = 1;
  for (; tux != 0; tux--) {
    int pur;
    cin >> pur;
    foo = foo + pur;
    bar = bar + 1;
    if (foo * quz >= bar * baz) {
      baz = foo;
      quz = bar;
    }
  }
  cout << 1.0 * baz / quz << endl;
}
int main() {
  solve();
  return 0;
}
