What begins with the letter "e" and only contains one letter?
An envelope begins with letter "e" and contains only one letter.
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.
### Instruction: What begins with the letter "e" and only contains one letter?
### Input: 
### Response: An envelope begins with letter "e" and contains only one letter.