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

#define MAX_CAPACITY 101

int lanternChain[MAX_CAPACITY];
int front = 0;
int rear = -1;
int size = 0;
int capacity;
void addLantern(int colorCode) {
    if (size < capacity) {
        rear = (rear + 1) % capacity;
        lanternChain[rear] = colorCode;
        size++;
    }
}
int removeLantern() {
    if (size > 0) {
        int removedColor = lanternChain[front];
        front = (front + 1) % capacity;
        size--;
        return removedColor;
    }
    return -1; 
}

int isEmpty() {
    return (size == 0);
}

int main() {
    int n;
    if (scanf("%d", &n) != 1) {
        printf("Invalid input\n");
        return 0;
    }
    
    if (n < 1 || n > 100) {
        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");
            } e
            lse {
                int removedColor = removeLantern();
                printf("%d\n", removedColor);
            }
        } else {
            int colorCode = atoi(operation);
            if (colorCode < 1 || colorCode > 1000) {
                printf("Invalid input\n");
                return 0;
            }
            
            addLantern(colorCode);
        }
    }
    
    return 0;
}