Problem:       
    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

Solution (in PYTHON):

Solution:
import sys
                                 #HAI
                                 #I HAS A TUX
TUX = int(sys.stdin.readline())  #GIMMEH TUX
FOO = 0                          #I HAS A FOO ITS 0
BAR = 0                          #I HAS A BAR ITS 0
BAZ = 0                          #I HAS A BAZ ITS 0
QUZ = 1                          #I HAS A QUZ ITS 1
                                 #TUX IS NOW A NUMBR
while TUX > 0:                   #IM IN YR LOOP NERFIN YR TUX TIL BOTH SAEM TUX AN 0
  TUX -= 1
                                 #I HAS A PUR
  PUR = int(sys.stdin.readline())#GIMMEH PUR
                                 #PUR IS NOW A NUMBR
  FOO += PUR                     #FOO R SUM OF FOO AN PUR
  BAR += 1                       #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
  if max (FOO * QUZ, BAR * BAZ) == FOO * QUZ:       
                                 #O RLY?
                                 #YA RLY
     BAZ = FOO                   #BAZ R FOO
     QUZ = BAR                   #QUZ R BAR
                                 #OIC
                                 #IM OUTTA YR LOOP
                                 #BAZ IS NOW A NUMBAR
print BAZ * 1.0/QUZ              #VISIBLE SMOOSH QUOSHUNT OF BAZ QUZ
                                 #KTHXBYE