#include <bits/stdc++.h>
using namespace std;
int main() {
  int tux;
  cin >> tux;
  float foo = 0, bar = 0, baz = 0, quz = 1;
  for (int i = 0; i < tux; ++i) {
    float pur;
    cin >> pur;
    foo = foo + pur;
    bar = bar + 1;
    if ((foo * quz) > (bar * baz)) {
      baz = foo;
      quz = bar;
    }
  }
  cout << baz / quz;
  return 0;
}
