Please provide a detailed clear solution, will upvote

A blind signature allows a party, say Alice, to get the signature of another party, say Bob, without allowing Bob to see the message being signed. It can be used to build an e-cash system as follows (assume Alice is a customer and Bob is the bank). In the e-cash system, each e-coin has two attributes: a serial number, and the denomination of the coin (e.g., $1,$5, etc.). The coin must be signed by the bank before it can be used. The serial number allows the bank to detect double-spending (i.e., after verifying the validity of the signature, a merchant should also check with the bank if the coin has been used before). However, it also allows the bank to trace the shopping behavior of the user. Below is a solution for the problem using blind signature. 1. Alice first randomly chooses a large serial number T, and then creates a coin C=(T,D) where D denotes the denomination of the coin. 2. Alice then blinds the coin C to get C, and sends (C,D) to the bank. 3. The bank signs the blinded coin C', and deducts D dollars from Alice's account. 4. The bank sends the blind signature S for C to Alice, who then uses the blind factor in step 2 to recover a signature S for the original coin C. However, there is a potential security problem - Alice can let the bank sign anything. For example, C=(T,$10), but Alice can send (C,$1) to the bank which cannot verify if the denomination of the coin is indeed $1 or not. Modify the above protocol so that Alice cannot cheat except with low probability (e.g., 0.01% )