#!/usr/bin/python


import sys, string


total = 0

number = 0


print """Please enter a positive integer, and I will add all numbers between one and
that number"""
textline = sys.stdin.readline()
try:
        number = string.atoi(textline)
        if number == 0:
                raise InvalidNumberError
except:
        print "You typed an invalid number.  Exitting..."
        sys.exit(1)


for num in range(1, number + 1):
        total = total + num


print "When you add all the numbers from one to ", number, ", the result is ", total, "."