#include <bits/stdc++.h>
using namespace std;
int main() {
  double n, sum = 0, BAR = 0, BAZ = 0, QUZ = 1, a, i;
  cin >> n;
  for (i = 0; i < n; i++) {
    cin >> a;
    sum = sum + a;
    BAR += 1;
    if (sum * QUZ > BAR * BAZ) {
      BAZ = sum;
      QUZ = BAR;
    }
  }
  cout << BAZ / QUZ;
  return 0;
}
