$ euler -c 1
Multiples of 3 and 5
====================

URL: https://projecteuler.net/problem=1
Duration: 3.166µs
Answer: 233168

$ euler -c 2
Even Fibonacci numbers
======================

URL: https://projecteuler.net/problem=2
Duration: 368ns
Answer: 4613732

$ euler --help
Usage:
  euler [OPTIONS]

Application Options:
  -c, --challenge= Challenge ID

Help Options:
  -h, --help       Show this help message