"This is my step ladder. I never knew my real ladder." - Louis C.K.

Let's assume for a minute that your favorite thing in the world is a dictionary full of, well, words. Your second-favorite thing is to invent games involving said dictionary, although nobody ever wants to play them with you because they involve said dictionary. Anyway, here's your most recent addition to the world of gaming!

An edit step is a transformation from one word \(x\) to another word \(y\) such that \(x\) and \(y\) are words in the dictionary, and \(x\) can be transformed to \(y\) by adding, deleting, or changing one letter. The transformations from dig to dog and from dog to do are both edit steps. An edit step ladder is a lexicographically ordered sequence of words \(w_1, \ldots, w_n\) such that the transformation from \(w_i\) to \(w_{i+1}\) is an edit step for all \(1 \leq i < n\).

For a given dictionary, you are to compute the length of the longest edit step ladder.


The input to your program consists of the dictionary: a set of lowercase words in lexicographic order at one word per line. No word exceeds 16 letters and there are at most 25,000 words in the dictionary.


The output consists of a single integer, the number of words in the longest edit step ladder.

Sample Input


Sample Output


This is challenge 10029 of the ACM International Collegiate Programming Contest. Test input is provided by uDebug.

Upload Solution

Please log in to submit your solution.


Difficulty (2 votes)
Average test runtime 0.25
Points (changes over time) 10
Tried by 7 users
Solved by 6 users

Global ranking

# Name Runtime Points worth
1 ,s/java/NaN/gi 0.15 16
2 贝尔恩德 0.21 11
3 JB 0.24 10
4 Mac 0.26 9
5 Dark 0.27 9
6 Skøgland 0.40 6