import java.util.*;
 
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String line = sc.nextLine().trim();
 
        // 提取 [] 中的内容
        line = line.substring(line.indexOf('[') + 1, line.indexOf(']'));
 
        if (line.length() == 0) {
            System.out.println(0);
            return;
        }
 
        String[] parts = line.split(",");
        int[] nums = new int[parts.length];
 
        for (int i = 0; i < parts.length; i++) {
            nums[i] = Integer.parseInt(parts[i].trim());
        }
 
        // 核心逻辑
        Set<Integer> set = new HashSet<>();
        for (int num : nums) set.add(num);
 
        int maxLen = 0;
 
        for (int num : set) {
            if (!set.contains(num - 1)) {
                int cur = num;
                int len = 1;
 
                while (set.contains(cur + 1)) {
                    cur++;
                    len++;
                }
 
                maxLen = Math.max(maxLen, len);
            }
        }
 
        System.out.println(maxLen);
    }
}

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

bnVtcz1bMSwzLDUsNyw5LDExXQ==

nums=[1,3,5,7,9,11]