DMOPC '22 Contest 4 P4 - Anki Reviews
View as PDFEdward just lost his Anki streak of 981 days! Completely panic-stricken, he scrambles for ways to recover his lost streak. Luckily, he remembered that the streak calculator works based on Anki's time zone, and that changing the time zone could have the potential to recover some of his streak. Specifically, Edward has logged  reviews, the 
-th review at minute 
. In his world, each day consists of 
 minutes. If he picks a time zone that resets at minute 
, then each day spans the minutes 
 for some integer 
. A day is considered active if Edward did at least one review that day, and a streak is a consecutive sequence of active days. Your job is to determine the longest possible length of the longest streak, given that Edward picks an optimal value of 
.
Constraints
Subtask 1 [5%]
Subtask 2 [20%]
Subtask 3 [75%]
No additional constraints.
Input Specification
The first line contains  integers 
 and 
.
The next line contains  space-separated integers 
. These are given in non-decreasing order.
Output Specification
Output the length of the longest streak, given that Edward picks an optimal value of .
Sample Input
5 3
3 5 5 7 16
Sample Output
3
Explanation for Sample
Edward can pick a reset time of . Then, the 
th day consists of minutes 
, the 
st day consists of minutes 
, the 
nd day consists of minutes 
, and so on. Days 
, and 
 are active, so the longest streak is 
 days.
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