#include <bits/stdc++.h>
int main() {
  int tux;
  scanf("%d", &tux);
  int foo = 0, bar = 0, baz = 0, quz = 1;
  for (int i = 0; i < tux; i++) {
    int pur;
    scanf("%d", &pur);
    foo += pur;
    bar += 1;
    if (foo * quz >= bar * baz) {
      baz = foo;
      quz = bar;
    }
  }
  printf("%lf\n", (double)baz / quz);
}
