Write a program that prints the longest substring which the letters occur in alphabetical order.

longest_subString.py

si = ['azcbobobegghakl', 'abcdefghijklmnopqrstuvwxyz', 'nqlkcvjkwytg', 'bovgfeiromsncq']
for s in si:
    max_subStr = ''
    for i in range(len(s)):
        sub_string = s[i]
        char_count = 0
        while i + 1 < len(s) and s[i]<=s[i+1]:
            char_count+=1
            i+=1
            sub_string+=s[i]
        if len(sub_string)> len(max_subStr):
            max_subStr = sub_string
    print(max_subStr)