#include <bits/stdc++.h>
using namespace std;
int main() {
  int TUX, PUR, c, d;
  int num, FOO = 0, BAR = 0, BAZ = 0, QUZ = 1;
  scanf("%d", &TUX);
  for (int i = 0; i < TUX; i++) {
    scanf("%d", &PUR);
    FOO += PUR;
    BAR++;
    if (FOO * QUZ >= BAR * BAZ) {
      BAZ = FOO;
      QUZ = BAR;
    }
  }
  double daaa = BAZ * 1.0 / QUZ;
  printf("%.6lf", daaa);
}
