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

#define MAX_CAPACITY 101

int laternchain[MAX_CAPACITY];
int front =0;
int rear=-1;
int size=0;
int capacity;
int n;
void addLatern(int colorCode)
{
    if(size<capacity)
    {
        rear=(rear+1)%capacity;
        laternchain[rear]=colorCode;
        size++;
    }
}

int removaLatern()
{
    if(size>0)
    {
        int removedcolor=laternChain[front];
        front=(front+1)%capacity;
        size--;
        return removedcolor;
    }
}

int isEmpty()
{
    return(size==0);
    
}
int main()
{
    if(scanf("%d",&n)!=1)
    {
        printf("Invalid input\n");
        return 0;
    }
    capacity=n+1;
    for(int i=0;i<n;i++)
    {
        char operation[10];
        if(scanf("%s",&operation)!=1)
        {
            printf("Invalid input\n");
            return 0;
        }
        if(operation[0]=='-')
        {
            if(isEmpty())
            {
                printf("the chain was empty\n");
            }
            else
            {
                int removedColor=removeLatern();
                printf("%d\n",removedColor)
            }
        }
        else
        {
            int colorCode=atoi(operation);
            if(colorCode<1||colorCode>1000)
            {
                printf("Invalid input\n");
                return 0;
            }
            addLatern(colorCode);
        }
    }
    return 0;
}