#include <bits/stdc++.h>
using namespace std;
int main() {
  istream& in = cin;
  int TUX;
  in >> TUX;
  int FOO = 0, BAR = 0, BAZ = 0, QUZ = 1;
  for (int i = 0; i < TUX; i++) {
    int PUR;
    in >> PUR;
    FOO = FOO + PUR;
    BAR = BAR + 1;
    if (FOO * QUZ <= BAR * BAZ) continue;
    BAZ = FOO;
    QUZ = BAR;
  }
  printf("%.6lf\n", (double)BAZ / QUZ);
}
