# Problem 3
# 15.0/15.0 points (graded)
# Assume s is a string of lower case characters.

# Write a program that prints the longest substring of s in which the letters occur in alphabetical order. For example, if s = 'azcbobobegghakl', then your program should print

# Longest substring in alphabetical order is: beggh
# In the case of ties, print the first substring. For example, if s = 'abcbcd', then your program should print

# Longest substring in alphabetical order is: abc
# Note: This problem may be challenging. We encourage you to work smart. If you've spent more than a few hours on this problem, we suggest that you move on to a different part of the course. If you have time, come back to this problem after you've had a break and cleared your head.


# ----------------Under line Code --------------------------------#

result, current = '',''

for alphabet in s:
    if (current == ''):
        current = alphabet
    elif (current[-1] <= alphabet):
        current += alphabet
    elif (current[-1] > alphabet):
        if (len(result) < len(current)):
            result  = current
            current = alphabet
        else:
            current = alphabet
if (len(current) > len(result)):
    result = current

print(result)