      
    HAI  
    I HAS A TUX  
    GIMMEH TUX  
    I HAS A FOO ITS 0  
    I HAS A BAR ITS 0  
    I HAS A BAZ ITS 0  
    I HAS A QUZ ITS 1  
    TUX IS NOW A NUMBR  
    IM IN YR LOOP NERFIN YR TUX TIL BOTH SAEM TUX AN 0  
    I HAS A PUR  
    GIMMEH PUR  
    PUR IS NOW A NUMBR  
    FOO R SUM OF FOO AN PUR  
    BAR R SUM OF BAR AN 1  
    BOTH SAEM BIGGR OF PRODUKT OF FOO AN QUZ AN PRODUKT OF BAR BAZ AN PRODUKT OF FOO AN QUZ  
    O RLY?  
    YA RLY  
    BAZ R FOO  
    QUZ R BAR  
    OIC  
    IM OUTTA YR LOOP  
    BAZ IS NOW A NUMBAR  
    VISIBLE SMOOSH QUOSHUNT OF BAZ QUZ  
    KTHXBYE  
    

Input

The input contains between 1 and 10 lines, i-th line contains an integer number xi (0 ≤ xi ≤ 9).

Output

Output a single real number. The answer is considered to be correct if its absolute or relative error does not exceed 10 - 4.

Examples

Input

3
0
1
1


Output

0.666667
#include <bits/stdc++.h>
const int MAX_LEN = 1010;
using namespace std;
template <typename U, typename V>
string to_string(pair<U, V>);
string to_string(const string& e_) { return "\"" + e_ + "\""; }
string to_string(char e_) { return "\'" + string(1, e_) + "\'"; }
string to_string(bool e_) { return e_ ? "true" : "false"; }
template <typename T>
string to_string(T e_) {
  string s_ = "[ ";
  for (const auto& x_ : e_) s_ += to_string(x_) + " ";
  return s_ + "]";
}
template <typename U, typename V>
string to_string(pair<U, V> e_) {
  return "(" + to_string(e_.first) + ", " + to_string(e_.second) + ")";
}
void dbg_str() { ; }
template <typename U, typename... V>
void dbg_str(U u, V... v) {
  ;
  dbg_str(v...);
}
double t, x, s, y, z;
double m = 1;
int main() {
  scanf("%lf", &t);
  while (t--) {
    scanf("%lf", &x);
    s += x;
    ++y;
    if (s * m > z * y) {
      z = s;
      m = y;
    }
  }
  printf("%.6f\n", z / m);
}
