''' Purpose: introduce nested looping.
for a user-supplied n, loop n times where on the r-th iteration,
the integers from 1 to r are printed out.
'''
# get n
reply = input( 'Enter number: ' )
n = int( reply )
# performed the repeated printing of a number series
for r in range( 1, n + 1 ) :
# print the numbers from 1 to r
for j in range(1, r + 1):
print(j, end=' ')
print() # prints nothing and moves cursor to next line