# Homework 18, challenge: Sum 1..N.
#
# Prompt for a positive whole number n. Compute 1 + 2 + ... + n with
# a for loop and a running total. Print:
#   Sum from 1 to N is S
# Then print the closed-form result n * (n + 1) // 2 on the next line
# to confirm the two match.
#
# Run with: python exercises/18/homework/04-sum-1-to-n.py

# Your code goes here: