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

#define max(a, b) ((a) < (b) ? (b) : (a))
#define min(a, b) ((a) > (b) ? (b) : (a))

struct vector
{
    int size, reserved;
    int *list;
};

typedef struct vector Vector;

Vector *new_vector()
{
    Vector *v = malloc(sizeof(Vector));
    v->size = 0;
    v->reserved = 0;
    v->list = NULL;
    return v;
}

void vector_push_back(Vector *v, int value)
{
    if (v->size == v->reserved)
    {
        v->reserved = (v->reserved + 1) * 2;
        int *new_list = malloc(sizeof(int) * v->reserved);
        memcpy(new_list, v->list, v->size * sizeof(int));
        free(v->list);
        v->list = new_list;
    }
    v->list[v->size++] = value;
}

#define MAX 100000

Vector *g[MAX];
int queue[MAX], tail, head;

void push_back(int value){
    queue[tail] = value;
    tail = (tail + 1)%MAX;
}

void push_front(int value){
    head = (head - 1 + MAX)%MAX;
    queue[head] = value;
}

int pop_front(){
    int first = queue[head];
    head = (head + 1)%MAX;
    return first;
}

int pop_back(){
    tail = (tail - 1 + MAX)%MAX;
    return queue[tail];
}

int size(){
    return (head<=tail?tail-head:MAX-head+tail);
}

void print_queue(){
    int i;
    for (i = head; i!=tail; i = (i+1)%MAX)
        printf("%d ", queue[i]);
    printf("\n");
}

int main()
{
    while (1) {
        int t, x;
        scanf("%d", &t);
        if (t == 0)
            break;
        else if (t == 1) {
            printf("%d\n", pop_front());
        } else if (t == 2) {
            printf("%d\n", pop_back());
        } else if (t == 3) {
            scanf("%d", &x);
            push_front(x);
        } else if (t == 4) {
            scanf("%d", &x);
            push_back(x);
        }
        print_queue();
    }

    /*int n, i, j;
    scanf("%d",&n);
    for (i=0;i<n;++i)
        g[i] = new_vector();
    for (i = 1; i < n; ++i)
    {
        int x;
        scanf("%d", &x);
        vector_push_back(g[x], i);
    }
*/

    return 0;
}