'''
Exercise 7: Sum of the First n Positive Integers
Write a program that reads a positive integer, n, from the user and then displays the
sum of all of the integers from 1 to n. The sum of the first n positive integers can be
computed using the formula:
sum = (n)(n + 1)/2
'''

n = int(input('Enter a positive integer: '))

sm = int(n * (n + 1) * 0.5) 
print('The sum of numbers from 1 to {} is {}'.format(n,sm))