#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int a;
  cin >> a;
  int foo = 0;
  int bar = 0;
  int baz = 0;
  int quz = 1;
  for (; a > 0; a--) {
    int pur;
    cin >> pur;
    foo = foo + pur;
    bar = bar + 1;
    if (foo * quz > bar * baz) {
      baz = foo;
      quz = bar;
    }
  }
  std::cout.setf(std::ios::fixed);
  std::cout.precision(6);
  cout << float(baz) / float(quz) << endl;
  return 0;
}
