#include <bits/stdc++.h>
int main() {
  float ans;
  int n, a, b, c, d, num;
  scanf("%d", &n);
  a = 0;
  b = 0;
  c = 0;
  d = 1;
  while (n--) {
    scanf("%d", &num);
    a = a + num;
    b = b + 1;
    if (a * d >= b * c) {
      c = a;
      d = b;
    }
  }
  ans = (float)c;
  ans = ans / d;
  printf("%f\n", ans);
  return 0;
}
