Challenge: Longest Unique Stretch

Lab Python Intermediate 20 points

Read a word and print the length of the longest stretch of neighbouring letters with no letter repeated.

Input

One word (letters only, at least 1 letter).

Output

One number.

Example

Input

abcabcbb

Output

Sample input available Sample output available

Editor

Python

Hints

Keep the letters in the window in a set.

If the new letter is already in the set, remove letters from the left until it isn't.

Solution explanation

Each letter enters and leaves the window at most once, so the total work is O(n).

Show solution

s = input().strip()
seen = set()
left = best = 0
for right in range(len(s)):
    while s[right] in seen:
        seen.remove(s[left])
        left += 1
    seen.add(s[right])
    best = max(best, right - left + 1)
print(best)

Output

Answer