PROGRAMMING:Third order determinant
###Task description
Read in a third-order determinant and output the value of the determinant.
###Input format:
There are three rows of input data, each row contains three numbers (all integers, absolute value not greater than 100), representing a third-order determinant.
###Output format:
Outputs the value of the determinant.
###Input example:
```in
1 2 3
6 5 4
8 7 9
```
###Output example:
```out
-21
```
answer：If there is no answer, please comment
Read in a third-order determinant and output the value of the determinant.
###Input format:
There are three rows of input data, each row contains three numbers (all integers, absolute value not greater than 100), representing a third-order determinant.
###Output format:
Outputs the value of the determinant.
###Input example:
```in
1 2 3
6 5 4
8 7 9
```
###Output example:
```out
-21
```
answer：If there is no answer, please comment