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

struct Node {
  char c; // 大写 or 小写
  struct Node *prev;
  struct Node *next;
  struct Node *same; // 相同的类型的下一个结点
};

// reverse string
struct List {
  int count;
  struct Node *head;
  struct Node *lower; // 最近一个小写
  struct Node *upper; // 最近一个大写
};

struct Node *createNode(char c) {
  struct Node *node = malloc(sizeof(struct Node));

  if (node == NULL) {
    exit(0);
  }

  node->c = c;
  node->prev = NULL;
  node->next = NULL;
  node->same = NULL;
  return node;
}

void insertAtHead(struct List *list, char c) {
  struct Node *node = createNode(c);

  if (c == 'm' || c == 'M') {
    return;
  }

  list->count = list->count + 1;

  if (list->head != NULL) { // 链表不为空
    node->next = list->head;
    list->head->prev = node;
    list->head = node;
  } else { // 链表为空
    list->head = node;
  }

  if (c >= 'a' && c <= 'z') { // 小写
    node->same = list->lower;
    list->lower = node;
  } else { // 大写
    node->same = list->upper;
    list->upper = node;
  }
}

void deleteNode(struct List *list, int Upper) {
  if (list->count == 0) {
    return;
  }

  struct Node *del_node; // 需要删除的结点
  if (Upper) {
    del_node = list->upper;
  } else {
    del_node = list->lower;
  }

  if (del_node != NULL) {
    if (del_node->prev != NULL) { // 不是头结点
      del_node->prev->next = del_node->next;
      if (del_node->next != NULL) {
        del_node->next->prev = del_node->prev;
      }
    } else {
      list->head = del_node->next;
      if (list->head != NULL) {
        list->head->prev = NULL;
      }
    }
    if (Upper) {
      list->upper = del_node->same;
    } else {
      list->lower = del_node->same;
    }
    list->count = list->count - 1;
    free(del_node);
  }
}

void displayListKofList(struct List *list, int k) {
  struct Node *iter = list->head;
  char *p = malloc(k + 1);
  for (int i = 0; i < k; i++) {
    if (iter) {
      *(p + k - i - 1) = iter->c;
      iter = iter->next;
    }
  }
  *(p + k) = '\0';
  printf("%s", p);
}

int main() {
  struct List list;
  list.head = NULL;
  list.lower = NULL;
  list.upper = NULL;
  list.count = 0;

  int q;
  scanf("%d", &q);
  getchar();
  for (int i = 0; i < q; i++) {
    char c;
    int newline = 1;
    while ((c=getchar())!= '\n') {
      if (c == '?' && newline == 1) { // 如果是查询
        int k;
        scanf("%d", &k);
        displayListKofList(&list, k);
      } else {
        if (c == 'm') {
          deleteNode(&list, 0);
        } else if (c == 'M') {
          deleteNode(&list, 1);
        } else {
          insertAtHead(&list, c);
        }
      }
      newline = 0;
    }
  }
}