Edit this sentence to improve its grammar and make it more concise:
"The cat was so quiet that nobody noticed it was there."
"The cat was so quiet it went unnoticed."
Complete the following task based on the instruction and optional input provided.### Instruction:
Edit this sentence to improve its grammar and make it more concise:

### Input:
"The cat was so quiet that nobody noticed it was there."

### Output:
"The cat was so quiet it went unnoticed."