#!/usr/bin/python3
s = "zyxwvabcalkj"
alphabet = "abcdefghijklmnopqrstuvwxyz"
idx = 0
idx_2 = 0
big_index = 0
big_count = 0

while idx < len(s):
    idx_2 = idx
    cur_count = 1
    cur_idx = 0

    cur_idx = idx_2
    while idx_2 < len(s) - 1:
        if alphabet.index(s[idx_2]) <= alphabet.index(s[idx_2 + 1]):
            cur_count += 1
            idx_2 += 1
        else:
            break

    if cur_count > big_count:
        big_index = cur_idx
        big_count = cur_count

    idx += 1


a = big_index
b = big_index + big_count
print("Biggest string is: " + s[a:b])