In this problem, you'll be given Bob's public key
along with two messages and their corresponding signatures,
and your task will be to calculate a signature for the third message.
In the code, here is Bob's public key.
This is the first message--387.
This is the signature for the first message.
The second message--only two.
And here's the signature for the second message.
And your task is to create a signature for the
message 774 and assign it to the variable s3.
We've provided a test function for you to use
to see if your value for s3 is correct.
