PROGRAMMING:Alternate character inverted triangle

According to the height read in, draw an inverted triangle with alternating st characters.
###Input format:
The input data contains no more than 50 positive integers n (1 ≤ n ≤ 30). Enter ^ Z with the keyboard or end the data entry when the end of the file is encountered.
###Output format:
Output inverted triangles alternated by St characters with n as high. When drawing each triangle, it should start another line.
###Input example:
```in
3 10
```
###Output example:
```out
STSTS
STS
S
STSTSTSTSTSTSTSTSTS
STSTSTSTSTSTSTSTS
STSTSTSTSTSTSTS
STSTSTSTSTSTS
STSTSTSTSTS
STSTSTSTS
STSTSTS
STSTS
STS
S
```







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