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