410339: GYM104010 K Pick a Pair

Friends play an interesting game with words. The goal of this game is arranging words in pairs.

Friends have $$$n$$$ words of the same length. They are choosing the largest number $$$k$$$ such that it is possible to divide the words into pairs so that words in each pair have common prefix of length at least $$$k$$$.

Find the maximum possible value of $$$k$$$.

The first line of input contains an even integer $$$n$$$ — number of words ($$$1 \leq n \leq 2\cdot 10^5$$$).

The following $$$n$$$ lines contain words that the friends have. All words have same length. Total words length is less or equal to $$$2 \cdot 10^6$$$.

Output maximal possible value of $$$k$$$.

4
aabc
aacc
bbbb
bbbd

2

2
a
b

0