Since the T20 World Cup,2012 is this year, selectors are keeping track of Suresh Raina's batting average in IPL-5. They want to see if his average is good enough for selection. You are provided with the runs scored by Raina in the matches he batted and you have to calculate his average. There would be some unbeaten knocks. The scores of the unbeaten knocks is counted inthe aggregate but the match is not. The unbeaten knocks are given in the form of negative numbers. Zero runs will be treated as out.

Input

Each line will contain the runs scored by  Raina in that match, with unbeaten knocks in negative integer.Input will stop when End-of-File is reached.

Output

Print the average of Raina in IPL-5. Average should be a real number, i.e, contains both integral and decimal part. Output the batting average upto 2 decimal places.

Example

Input:
10
40
-84
16


 Output:
 50

Input:
25
62
-18
16
24
45
10
-20
0

Output:
31.42