PROGRAMMING:Averaging
From the keyboard input a batch of positive integers (with - 1 as the end mark), calculate their average value and output.
###Input format:
The data is separated by a space, and the last number is the end tag - 1.
###Output format:
Output the average value, keep 2 decimal places, and finally wrap.
###Input example:
```in
1 3 5 7 9 11 13 15 17 19 -1
```
###Output example:
```out
ten
```
answer：If there is no answer, please comment
###Input format:
The data is separated by a space, and the last number is the end tag - 1.
###Output format:
Output the average value, keep 2 decimal places, and finally wrap.
###Input example:
```in
1 3 5 7 9 11 13 15 17 19 -1
```
###Output example:
```out
ten
```
answer：If there is no answer, please comment