PROGRAMMING:Calculate triangle area
Enter three numbers from the keyboard to represent the three sides of the triangle. If a triangle can be formed, the area of the triangle will be output, otherwise no will be output.
###Input format:
Please write the length of the three sides of the triangle here, for example:
3.1 4.2 5.3
###Output format:
Please output the area of triangle here, for example:
six point five zero six six one
###Input example:
```in
3.0 4.0 5.0
```
###Output example:
```out
six
```
answer：If there is no answer, please comment
###Input format:
Please write the length of the three sides of the triangle here, for example:
3.1 4.2 5.3
###Output format:
Please output the area of triangle here, for example:
six point five zero six six one
###Input example:
```in
3.0 4.0 5.0
```
###Output example:
```out
six
```
answer：If there is no answer, please comment