题目描述
problem
There are n cards with one integer from 1 to n and one blank card. Of these n + 1 cards, k cards are given, but 1 ≤ k ≤ n. You can write one integer from 1 to n on a blank card. I want to make a continuous sequence of integers as long as possible with just a given card.
Write a program that outputs the maximum length of a contiguous sequence of integers that can be made from a given card when the given card is entered.
input
The input consists of multiple datasets. Each dataset is given in the following format. The input ends on a line containing two zeros.
On the first line, two integers n (1 ≤ n ≤ 100000) and k (1 ≤ k ≤ n) are written in this order, separated by one blank. The following k line contains one integer. Written one by one, representing the integers written on the given k cards. Blank cards are represented by 0.
Of the scoring data, 40% of the points are 1 ≤ n ≤ 1000, 1 ≤ k ≤ 500, 20% of the points are 1 ≤ n ≤ 60000, 1 ≤ k ≤ 50000. Satisfy 1 ≤ n ≤ 100000, 1 ≤ k ≤ 100000.
The number of datasets does not exceed 5.
output
Outputs an integer on one line for each dataset.
Examples
Input
7 5
6
2
4
7
1
7 5
6
2
0
4
7
0 0
Output
2
4
Input
None
Output
None
输入格式
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输出格式
见题面