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

struct ListNode {
    int val;
    struct ListNode* next;
    struct ListNode* prev;
};

int* solution(struct ListNode* head, int* returnSize) {
    *returnSize = 0;
    struct ListNode* temp = head;
    while (temp) {
        (*returnSize)++;
        temp = temp->next;
    }
    
    int* result = (int*)malloc(*returnSize * sizeof(int));
    struct ListNode* current = head;
    int index = 0;
    while (current) {
        result[index++] = current->val;
        current = current->next;
    }
    return result;
}

struct ListNode* buildDoublyLinkedList(int* values, int size) {
    if (size == 0) return NULL;
    struct ListNode* head = (struct ListNode*)malloc(sizeof(struct ListNode));
    head->val = values[0];
    head->next = NULL;
    head->prev = NULL;
    
    struct ListNode* current = head;
    for (int i = 1; i < size; i++) {
        struct ListNode* newNode = (struct ListNode*)malloc(sizeof(struct ListNode));
        newNode->val = values[i];
        newNode->next = NULL;
        newNode->prev = current;
        current->next = newNode;
        current = newNode;
    }
    return head;
}

int main() {
    char line[10000];
    fgets(line, sizeof(line), stdin);
    line[strcspn(line, "\n")] = 0;
    
    int values[1000];
    int count = 0;
    if (strlen(line) > 2) {
        char* token = strtok(line + 1, ",]");
        while (token) {
            values[count++] = atoi(token);
            token = strtok(NULL, ",]");
        }
    }
    
    struct ListNode* head = buildDoublyLinkedList(values, count);
    int returnSize;
    int* result = solution(head, &returnSize);
    
    printf("[");
    for (int i = 0; i < returnSize; i++) {
        printf("%d", result[i]);
        if (i < returnSize - 1) printf(",");
    }
    printf("]\n");
    
    free(result);
    return 0;
}