PROGRAMMING:Seek circumference
Find the circumference when the radius is equal to 11, take 3.1416 as the circumference ratio, and keep 2 digits after the decimal point.
###Input format:
No input
###Output format:
Len = perimeter value
###Input example:
```in
There is no need to input this question
```
###Output example:
```out
len=69.12
```
answer：If there is no answer, please comment
###Input format:
No input
###Output format:
Len = perimeter value
###Input example:
```in
There is no need to input this question
```
###Output example:
```out
len=69.12
```
answer：If there is no answer, please comment