Ivana won the bet (Zvonko hadn’t foreseen this and suspects
that it is due to outside interference) and now Zvonko is
waiting for her at the movies. While he is waiting, he is
observing messages on a screen above him.
As Ivana is running late, Zvonko has been looking at the
screen for a while and noticed that some messages appeared on
the screen more than once. Naturally, he’s been writing down
all messages on a piece of paper. He wants to know the length
of the longest string that appeared at least twice (appears in
two different positions on the paper).
Input
The first line of input contains an integer $L~ (1 \leq L \leq 200\, 000)$, the
length of the string Zvonko wrote down.
The second line contains a string of $L$ lowercase letter of the English
alphabet.
Output
Output the length of the longest string that appears twice
on a single line. If there is no such string, output zero.
Sample Input 1 
Sample Output 1 
11
sabcabcfabc

3

Sample Input 2 
Sample Output 2 
18
trutrutiktiktappop

4

Sample Input 3 
Sample Output 3 
6
abcdef

0
