Find the first positive number in a list of integers. Output the number or a letter indicating no positive number was found.
[1, -4, -5, 2, 0, -20]
1
Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
Find the first positive number in a list of integers. Output the number or a letter indicating no positive number was found.

### Response:
1