C. WTF?
time limit per test
2 seconds
memory limit per test
256 megabytes
input
stdin
output
stdout

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