Construct a regular expression to identify strings that start with the letter "s".
The regular expression to identify strings that start with the letter "s" is `^s` or `^[sS]` if you want to make it case-insensitive.
Complete the following task based on the instruction and optional input provided.### Instruction:
Construct a regular expression to identify strings that start with the letter "s".

### Output:
The regular expression to identify strings that start with the letter "s" is `^s` or `^[sS]` if you want to make it case-insensitive.