// editor1
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define MAX 100
typedef struct{
    int data[MAX];
    int front;
    int rear;
}queue;
void initQueue(queue*q){
    q->front=0;
    q->rear=0;
}

int isEmpty(queue*q){
    return q->front ==q->rear;
}
int isFull(queue*q)

    return (q->rear+1)%MAX == q->front
    
}
void enqueue(queue*q,int value){
    if(isFull(q)){
        printf("Invalid input");
        exit(0);
    }
    q->rear=(q->rear+1)%MAX
    q->data[q->rear]=value;
    
}
void dequeue(queue*q)
{
if (isEmpty(q)){
    return -1
}
q->front=(q->front+1)%MAX
return q->data[q->front++];
}

    return q->data[q->front++];

int main{
    int n;
    Queue q;
    initQueue(&q);
    if(scanf(&d,&n)!=1||n<=0){
        printf("invalid input");
        return 0;
    }
    
    for(int i =0;i<n;i++){
        char input[20];
        if(scanf("%s",input)!=1){
            printf("Invalid input")
            return 0;
        }
        if(strcmp(input,"-")==0){
            if(isEmpty(&q)){
            printf("the chain was eempty")
            }
        }
    }
}