#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>

#define HASH_SIZE 100003

typedef struct HashNode {
    int key;
    struct HashNode* next;
} HashNode;

HashNode* hashTable[HASH_SIZE];

int hash(int key) {
    return ((key % HASH_SIZE) + HASH_SIZE) % HASH_SIZE;
}

void insert(int key) {
    int index = hash(key);
    HashNode* newNode = (HashNode*)malloc(sizeof(HashNode));
    newNode->key = key;
    newNode->next = hashTable[index];
    hashTable[index] = newNode;
}

bool contains(int key) {
    int index = hash(key);
    HashNode* current = hashTable[index];
    while (current) {
        if (current->key == key) return true;
        current = current->next;
    }
    return false;
}

int solution(int* nums, int numsSize) {
    if (numsSize == 0) return 0;
    
    // Initialize hash table
    for (int i = 0; i < HASH_SIZE; i++) {
        hashTable[i] = NULL;
    }
    
    // Insert all numbers into hash set
    for (int i = 0; i < numsSize; i++) {
        insert(nums[i]);
    }
    
    int maxLength = 0;
    
    for (int i = 0; i < numsSize; i++) {
        int num = nums[i];
        // Check if this number is the start of a sequence
        if (!contains(num - 1)) {
            int currentNum = num;
            int currentLength = 1;
            
            // Count consecutive numbers
            while (contains(currentNum + 1)) {
                currentNum++;
                currentLength++;
            }
            
            if (currentLength > maxLength) {
                maxLength = currentLength;
            }
        }
    }
    
    return maxLength;
}

int main() {
    char line[10000];
    fgets(line, sizeof(line), stdin);
    
    int nums[1000];
    int count = 0;
    
    char* ptr = strchr(line, '[');
    if (ptr) {
        ptr++;
        char* token = strtok(ptr, ",]");
        while (token != NULL) {
            nums[count++] = atoi(token);
            token = strtok(NULL, ",]");
        }
    }
    
    int result = solution(nums, count);
    printf("%d\n", result);
    
    return 0;
}