#include<stdio.h>
#include<string.h>
#define MAX_SIZE 1000
int deque[MAX_SIZE];
int front=MAX_SIZE/2,rear=MAX_SIZE/2-1;
void join_front(int x){
    if(front>0){
        front--;
        deque[front]=x;
        
    }
}
void display(){
    for(int i=front;i<=rear;i++){
        printf("%d",deque[i]);
    }
    printf("\n");
    
}
int main(){
    int n;
    scanf("%d",&num);
    int num;
    for(int i=0;i<n;i++){
        scanf("%s",cmd);
        if(strcmp(cmd,"join_front")==0){
            scanf("%d",&num);
            join_front(num);
        }else if(strcmp(cmd,"join_rear")==0){
            scanf("%d",&num);
            join_rear(num);
        }else if(strcmp(cmd,"issue")==0){
            issue();
        }else if(strcmp(cmd,"display")==0){
            
        }
    }
    return 0;
}