#include <bits/stdc++.h>
using namespace std;
int main() {
  int it;
  int TUX;
  cin >> TUX;
  int FOO = 0, BAR = 0, BAZ = 0, QUZ = 1;
  for (int i = TUX; i != 0; i--) {
    int PUR;
    cin >> PUR;
    FOO += PUR;
    BAR++;
    it = ((max((FOO * QUZ), (BAR * BAZ))) == (FOO * QUZ));
    if (it) {
      BAZ = FOO;
      QUZ = BAR;
    }
  }
  cout << ((double)BAZ) / ((double)QUZ) << endl;
  return 0;
}
